Overwintering Koi Under Thick Ice

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September/October 2009

Jamie Beyer

Overview of two ponds each with their own bucket containing the air pump. There is about 12" of snow on the ice surface. Note that there is very little disturbance to the ponds checking the aeration points. In the foreground, you can easily see my footprints going out to check the ice dome that is mostly covered by snow.

The winter of 2009 was brutal in the Midwest. The lows on January 15th and 16th hovered around minus 21° F. in central Iowa. To overwinter koi in outside ornamental fish ponds in these conditions is something a lot of koi owners have never experienced. It can be done, however, and it is not that complicated.

Three Techniques

There are three basic techniques for overwintering koi where there are heavy icing conditions.

• The koi can be removed from their pond and brought inside a heated building or greenhouse.

• A structure can be built over their pond that collects heat from solar radiation, and/or heat can be added.

• The last technique and the easiest by far, is to leave them in their pond with the addition of aeration, and let it ice over naturally.

Most koi owners are very nervous about keeping koi outside under ice. This is a very “touchy” subject to serious koi hobbyists. They simply will not trust leaving their valuable fish in these conditions. They may not see the fish for three months, and when the winter winds are howling and it is minus 20° F., most hobbyists fear the worst. To make matters worse, there are articles warning that water colder than 39° F. can be lethal or at the very least, deform koi. Unfortunately, this kind of information is misleading and not factual, and, in fact, the ice layer actually protects them from the brutality of winter.

Koi (a variety of carp with fancy coloration and scalation) need a cold rest period in their seasonal cycle. They have evolved to endure cold water winter conditions. This cycle includes a gradual acclimation to the onset of winter and cold water over time. This is naturally done in the late summer and fall when, as the weather cools, they become acclimatized to very cold conditions. Taking a koi that has been in 60 to 70° F water and immediately placing that fish under ice in a winter pond would most likely prove lethal.

We can get some clues as to how our koi can overwinter by observing carp that overwinter just fine in Midwest lakes and streams. Streams will have open water in the channel where the water flows fast. It is churning and mixing the entire water column all the time. The water is continually being exposed to subzero air temperatures. The actual water temperatures in these streams are very close to 32° F. In my own aerated 10,000-gal koi pond system that is 5.5´ deep the bottom temperature was just above 32° this past winter. I have checked my thermometers for accuracy and they are correct. All of my 38 large koi survived the winter in great shape. I have been using the same technique for the last 17 years and have always been successful.

How to be Successful

So, just how can a serious koi hobbyist successfully overwinter their fish under thick ice? Let me explain some steps that will work for you.

This is an aeration point that is domed over that is more easily seen since the deep snow is not present. Notice the large air bubble under the ice and air escaping the ice in the foreground.

Pond design is always important for many reasons but having the right design for overwintering fish is rarely discussed. The best design for a koi pond is one that is open without a lot of convolutions to the edge. Avoid overcomplicated designs, such as islands, channels, peninsulas and similar additions that can create what are called “dead zones.” These zones are exactly that - DEAD - devoid of life due to low oxygen (O2)! It is difficult to adequately circulate the water in these areas and consequently they usually have lower O2 levels. They are likely to be lower in O2 all times of the year, but during winter when the pond circulation is even less, it can become a lethal area for your fish. You can reduce the possibility of these anoxic conditions in the dead zones by adding aeration points. If this is not done, then be very aware that these areas can contribute to fish kills during the winter.

It is important to start preparing for winter about a month or two before freeze-up (ice formation). Go through the fish collection and remove fish that are not wanted. Do this in the fall rather than the spring. The goal is to have as low a fish population as possible going into winter.

If there has been any salt added to the koi pond, water changes are needed to significantly reduce the concentration of it. Salt can lower the freezing point of water. So, a pond with salt can become super cooled. I do not have any direct experience with this situation, but I would venture to say that it could be lethal to fish.

Right before ice forms on the pond, the organic matter needs to be removed. If this is done any earlier, leaves can still blow in before it freezes. Once frozen the leaves do not blow into the pond as much. A lot of organic matter is not good for even a summer pond that is being circulated and filtered but this stuff in a pond that is going into winter spells almost certain death to our fish and the ecosystem of the pond.

The outside temperature on the day that this photograph was taken was 25° F. Notice the large hole in the ice. There are three 55-gal plastic drums shown in this picture. They provide structure for the fish to orient to. Not really necessary for overwintering koi but makes their pond more interesting for them.

By the time winter arrives, most of us have reduced the pond’s water circulation by shutting down high volume water pumps. Biological filtration becomes almost nonexistent due to bacteria going into their restive overwintering stages. These conditions can be lethal with a load of organic matter in the bottom of the pond. A few leaves are okay, but a thick layer of leaves during the winter can be lethal to large koi resting on the bottom next to them. These leaves give off toxic gases and reduce the O2 levels in that area. With heavy aeration this area’s O2 concentration can be increased, but whether it will be enough is in question. So, get that organic matter out of there to ensure the koi’s survival.

Obviously, fish need to enter winter in good vigor and health. Do not add any more fish to a collection for at least a month or two before the onset of cooler conditions. Even though new fish may have been quarantined there is a chance of disease or parasite transmission right before winter. Also, only quality foods should have been fed to the koi all summer and fall. These fish feedings should stop when the water temperatures drop to about 50° F.

With the fish in good shape and the organic load is minimized, the next step is to add aeration. Kloubec Koi Farms owner, Myron Kloubec, uses aeration in his earthen basin ponds. That is how he overwinters his large high quality beautiful koi in East Central Iowa. This is what Myron practices and recommends. That is how I also recommend overwintering ornamental koi ponds under heavy icing conditions.

The important aspects of aeration are to allow O2 to enter the water column and allow toxic gasses to escape. These toxic gases include carbon dioxide, hydrogen sulfide, among others. These gases arise from decomposition of organic matter as well as from fish and other critter respiration and excretions.

The temperature has dropped to about 10° F. The ice is close to doming over.

Adding aeration lowers a pond’s water temperature more quickly than without, but the temperature does not go any lower than what it would have been anyway. The ice in a typical Midwest pond that is 4000-gal and 30˝ deep can be as thick as 15 to 16˝. I have not seen ice thicker than that on this type of pond. Without any aeration the ice forms to within only 15˝ from the pond bottom. That water temperature at the very bottom is as close to the freezing point of water as it can get. By aerating the water you will lower the water temperature of the pond’s water more quickly, but the ice will actually be thinner especially around the area where the bubbles rise. The earth is an incredible heat source. It will continually supply enough heat to successfully overwinter our hardy fish in the Midwest without the pond completely freezing.

A lot of pond owners feel that they need to add a heater of some sort. Some common choices are stock tank heaters that may float or lie on the bottom. Of course, the heating element must be kept away from a rubber liner. The wattage of these can run in the 1500 watt range. This can amount to a lot of dollars to operate, but they do keep a hole in the ice open even in the coldest of conditions. There are smaller ones that use less wattage but the hole that is kept open is much smaller. Some O2 exchange will still occur in these ice free areas that in some years may be enough to overwinter fish. However, for the majority of fish ponds especially koi ponds, it is simply not enough. Circulation provided by aeration is still needed to aid in O2 exchange and to dissipate toxic gases. I cannot emphasize this enough.

Peering down through the one foot deep snow to see the bubbling. In this photo the bubbles cannot be seen due to lighting problems. This aeration point is all the circulation that is needed to overwinter a 10,000-gal pond with 38 large koi. These aeration points must be checked every day to insure that the air pumps are working.

Most of the time, I recommend not using any kind of supplemental heat. Lots of energy (and money) is wasted because the heat outside the hole that is maintained is immediately lost to the surrounding air. The heaters do not significantly raise an in-ground pond’s temperature. However, there may be specific instances where the use of supplemental heat is justified. For example, it is important to keep the area around the mouth of a skimmer box ice free if the main water pump, located there, is kept running. However, I generally recommend shutting these large pumps off and removing them as well as any kind of heater.

The best way to add aeration in our ornamental fish ponds is to use heavy duty air pumps. Aquarium air pumps will work okay as long as they are heavy duty and can take cold weather operation. These air pumps only take from 5 to 50 watts of power. I like to protect the air pump from the snow and rain by placing the pump in a 5-gal bucket with a lid on it. Cut a hole in the bottom large enough to allow the cord and air line tubing an exit point. Set the bucket on a couple of bricks so that is off the ground. A brick is placed on top so that the wind will not blow it over. Place the bucket at the side of the pond. Protecting the air pump inside the bucket will also prevent moisture from being pumped down the air line. This moisture will freeze and plug the air line. If this unlikely event should occur just simply abandon the frozen air line and put in another. You might think that the air line will collapse by the ice freezing around it. This does not happen.

Use silicone grade aquarium air line tubing. It stays flexible even during cold conditions. At the end of the air line use a heavy air stone. This needs to be placed in the very center of the pond and on the bottom. In larger ponds more than 20 to 25´ long, it would be wise to create two aeration points with two air stones.

This ice dome has not been pierced yet.

The amount of air that should be supplied to the air line is enough to create what I like to call a “good bubble” – a steady rise of bubbles. I do not like to see a raging boil, which can create currents in the pond. Situations where the fish have to fight a current can be lethal during those long winter months under the ice. They simply do not have that much energy with those kinds of cold conditions. They must be able to simply rest during the winter. After you add the air, watch the fish and see if they are swimming against a current. If so, then reduce the amount of air.

The aeration set-up needs to be checked every day to make sure that it is working. If it fails, for whatever reason, the O2 levels can drop in just a couple of days. If you are going on vacation, then either have an extra air pump running or have someone check what you have while you are gone. The extra air pump is a good idea anyway.

When the outside temperatures are 10 to 15° F or higher there should be an open hole in the ice where the bubbles rise. However, when the temperature drops lower the hole will “dome” over with a thin layer of ice. This is okay since you are pumping air under that dome. O2 is still being supplied to the area and the toxic gases and excess air can escape through micro pores in the dome ice. It is never smart to pound on the ice due to the possibility of shocking the fish but I like to just poke the thin dome ice to make sure that air is still escaping. Leave most of the dome but still poke a small hole. I like to see this dome form, since it keeps a lot of the really cold air from reaching the pond surface.

This is a dome that a hole has been created in.

Some may think that a water pump placed in the center of the pond with the outlet shooting straight up will provide the same benefit. Yes, it will until the intake of the pump plugs or it domes over. In this dome situation the pond surface is sealed off from the atmosphere and there would be no O2 exchange. Both disadvantages are difficult to deal with when you have heavy icing conditions. Use the air pump instead of the water pump.

Shoveling snow off the pond is something I would not do. You do not want to disturb the fish, and by shoveling you are creating quite a disturbance on the ice. You also could get to close to the thin ice near the aeration hole and fall through. Leaving the snow also creates more quiet dark areas in the pond, establishing a better winter environment for the fish. Besides, it can be a lot of work that is not necessary.

Overwintering valuable koi outside under heavy icing conditions is about as stressful to the koi owner as any other fish keeping task. You have to have faith that your aeration technique is going to work and your fish will come out of winter looking a bit thinner but still very healthy.

The other techniques that you can use to overwinter fish are to bring them inside or build a structure over their outdoor pond. Both of these options are a lot of work and expense. Leaving them outside in your properly designed pond, keeping the organic load low, keeping as low a fish population as possible and finally, providing adequate aeration, will ensure that your fish will be fine. These simple techniques discussed here can allow the hobby of keeping koi to prosper in areas where it is very cold.

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POND Trade Author - Jamie Beyer

Author Jamie Beyer

Location Boone IA

Company Midwest Waterscapes

Bio The very popular subject of adding water features to a garden is one that Jamie Beyer brings a lot of knowledge and enthusiasm to. Jamie is a Lifetime...

Read the full bio.



Mr. Beyer,

I read your most excellent article in the Sept/Oct issue of POND Trade. Very informative. I live along the IL/WI border in Richmond, IL.

I have wintered my Koi for five years and have not lost one yet. I use a small aerator that sits on the bottom of my pond with a air tube that sticks up above the water line approx 6”. This has served me well but the impeller is getting worn out. I have been searching for another low wattage aerator but that are hard to find. You mention them in your article but do not recommend a brand or supplier.

Could you be so kind as to give me a recommendation?


Clark D. Atwater

1. Posted on September 17th, 2009 at 12:39 pm.

By Clark D. Atwater.



It sounds like you have had a small water pump doing your circulation, which is fine. I do like the idea of the outlet sticking above the water surface. This way it will not necessarily dome over like I said in my article.

I do have a recommendation of an AIR PUMP that will be cheaper to run and is more reliable than a water pump. I am recommending running with two of these air pumps for reasons of a backup. Cause if one fails for whatever reason and you do not catch it -- this could prove fatal for your fish in just a week or two. One will work fine as long as you check it everyday -- double check to make sure it is getting air to the bottom of your fish pond.

Any good quality heavy-duty aerator for aquariums will work. It has to be heavy duty enough to pump air to the bottom of your pond. Depending on depth this could take a really heavy duty one.

I like to use an air pump called Luft. There are two or three models but the one I like to use is the small one -- it is brown and has a rheostat on the pump so that you can vary the output of the air. In really small ponds I like to reduce the airflow for reasons like I said in the article. For larger ponds I almost always use the full flow of air.

The link to the pump is as follows:

Keep me posted on how things work out for you.


2. Posted on September 17th, 2009 at 12:42 pm.

By Jamie Beyer of Midwest Waterscapes.


I was told that during the winter, you do NOT want your ail line to go all the way to the bottom of your pond, for it may super cool the water. Half way was what I was told.

3. Posted on February 1st, 2010 at 11:40 am.

By MIke.


There is a lot of misinformation on this aspect of aeration in a pond during the winter. Most of this information has been created by what people think should be done. Then it self-perpetuates because "it makes sense" to the unknowing. The idea gets incorporated into the mainstream literature without giving it a second thought. This concept may be true in very large ponds but not in backyard water gardens and Koi ponds.

I have carried out some experiments of where I placed the aeration point in a pond. The pond water temperature was the same at the bottom of the pond no matter where I place the aeration point as long it was in the center of the pond. This occurs for a very simple reason. Water that is aerated from mid column (half way down into the water) creates a plume of water welling up from that point. This water goes to the top and then circulates to the sides of the pond and then to the BOTTOM. In our relatively small bodies of water any circulation ends up circulating the whole pond unless you have dead zones (inlets, coves and the like will create these). I WANT the whole pond circulated – I do not want any dead zones.

As for "super cooling" the water. The water gets very cold no matter what. In my experiments the water will get to 32.1°F on the bottom of a 5.5 ´pond in a typical aerated Midwestern Koi pond in the middle of winter without ANY loss of fish. I have lost fish when I have failed to add aeration on a timely basis. In this instance I did not get my aeration going until after a layer of ice had developed. I learned 20 some years ago to have aeration going as soon as the water starts to cool. For that matter, I now have aeration going year round. This is in addition to my waterfall/stream pumps. I need to say that these waterfall/stream pumps are shut down when heavy freezing occurs. I do this because it way to risky. I do not want the stream to ice dam and overflow the sides. This can occur after a power outage where everything freezes or a chunk of ice breaks free in the stream and creates the ice dam.

I did say that I want to make sure that aeration is going as soon as the water starts to cool. If you start heavy aeration after the ice is already formed then you can possibly super cool a pond. The temperature can go from a relatively balmy 39°F to 32°F in a few minutes. This is pure conjecture on my part because I do not want to do this and jeopardize my fish or any of my client's fish.

I like to think of our ponds in a couple of different ways. First, a 3´ deep pond un-aerated pond that has a foot of ice on top of it – what do you think the temperature is of the water on the bottom? Remember the ice is only 2´ away from the bottom. You bet it is so close the temperature of the ice (32° F) that you could not tell the difference. Remember this is without any aeration. I have seen 2´ deep ponds 1000 gal. aerated ponds that has 18˝ of ice except where the aeration is and the calico shubunkin goldfish survive it in great shape. I would not want Koi in this situation only because isn't any space for them to swim.

Second, Midwestern streams in winter have heavy ice on them except where there is fast flowing water and the water is then exposed to the air. The entire stream water temperature is the same through out the water column. All of our fish survive these conditions very well, even Carp. We all know where Koi were developed from. Even though Koi are a distant relative of Carp I maintain that they are as hardy.

Please refer to the article that I wrote for POND Trade Magazine for more specifics.

I am working on some more info about overwintering fish under heavy icing conditions. Please stay tuned.

All in all – place that aeration point on the bottom of your pond, in the center.

Jamie Beyer
Midwest Waterscapes

4. Posted on April 26th, 2010 at 12:46 pm.

By Jamie Beyer of Midwest Waterscapes.


Mr Beyer,

Thank you for such an informative and reassuring article! I live in northern Wisconsin (zone 3b) where we do indeed get some very cold winters. Everything I've read has pretty much told me that while, yes, overwintering fish can be done it is a very risky endeavor, I'd be foolish to try it and if I really was a responsible koi owner, I'd just bring them in my basement and overwinter them there.

The thought of overwintering them indoors never really sat right with me. Living with an experienced angler (and having spent plenty of time myself out on the ice trying to catch panfish and walleye), I know that fish can survive just fine in very cold water. I also know that near freezing water temperatures are the norm for these fish (have lots of fancy schmancy fishing electronics to prove this). So, I never quite understood why my koi couldn't do the same.

I'm adding a addition to my pond this fall that will be 6' deep. It will be connected to the main pond by a 10" pvc tube. My plan is to herd the koi into the deep addition for the winter and block off the pvc so they can't go swimming back into the shallower main pond. It sounds like if I follow your tips, my koi should do just fine over the winter in their new deep home.

Thanks again for the advice!

5. Posted on August 17th, 2010 at 12:34 pm.

By Jennifer Baldini.


this was a very good article. Thank You. I am new to mid michigan and brought my one two yr old koi with me from IN. they have been raised in a tank and this is their first winter to be out and your article has really settled my nerves. thank you again.

6. Posted on October 9th, 2010 at 7:23 pm.

By cheri hayden.


Great article,
I need to subscribe to Pondtrade. So far i have built indoor ponds for clients with koi or fancies (not together) and enjoy the challenges and successes. Jennifer Baldini suggested a 10" pipe connection to deeper pond area, good idea but wouldnt a 20"pvc be safer, an old fat happy koi might end up plugging a 10" pipe?

7. Posted on October 16th, 2010 at 9:22 pm.

By alan kvasnik of Green Canvas Interiorscape.


I just purchased a home with a fish pond...It is roughly 15' long by 7' wide by 2' deep at the center...the previous owner told me that he brought the fish in the house over winter...Since it is only 2' deep, should I bring them in again or will an aerator work?? I live in Wisconsin, so the winters are self explanatory...

8. Posted on October 18th, 2010 at 12:28 pm.

By Tim.


Tim if you are in Southern Wisconsin and have a lot of the pond that is 2 feet deep you can use an aerator but it has to be working all the time.

9. Posted on October 28th, 2010 at 1:45 pm.

By Jamie Beyer of Midwest Waterscapes.


I have a very small pond (about 18" deep and 120 gallons) My son gave me 2 small Koi in May and they have lived happily all summer in my back yard. I have been trying to research what to do with them this winter and came across your article. I have found 2 types of deicers at the local farm store, one floats, and the other is submersible with a cage around it to protect the pond bottom. I have shut off and removed the pump and filter and cleaned out all the leaves. My question is which type of deicer should I use and do I still need to use an aerator? I live in mid-Mich. (zone 5) and the winters can be pretty cold.

10. Posted on November 22nd, 2010 at 1:51 pm.

By Mary Jo.


Mary Jo,

If you really want to keep them outside I would use the bottom deicer with the cage around it along with an aerator. It is a very small pond in a very cold situation. I do not know how big the Koi are but I can only guess that they are small in that small of a pond.

If it were my pond I would be bringing those fish inside. Remember that the fish need to be acclimated very slow to the warmer water inside. I would take a day to warm them up to inside temps and remember to bucket a bunch of the pond water to the inside tank. Jamie

11. Posted on November 24th, 2010 at 12:50 pm.

By Jamie Beyer of Midwest Waterscapes.


Thank you for the informative article. I have a new pond. It is about 6000 gallons, 20x14 feet in surface size, but only 2' deep. It is rectangular (no islands or peninsulas) in shape and lined with EPDM. I have 6 young koi (the largest is about 10"). We are in zone 5a (everyone here says that you need a maximum of 18" to overwinter fish in the pond, so I thought 24" would be safe). I have a 100w floating deicer, which is nicely keeping a small hole in the ice, but I don't know if that will be large enough to allow the proper gas exchange, and I also want a back up method in case the heater fails. So, I was researching my options and found your article to be the most informative I have found. My question is this, I was looking for a suitable aerator and found this: http://www.petsandponds.com/en/ponds-and-supplies/c28313/p16461748.html I'm in Canada, so the Canadian distributor is a plus, and the kit makes it easy, BUT, is it strong enough? And, the site says they don't recommend using an airpump to keep ice from covering the pond unless it is at leat 4 feet in depth. Do you think my koi would be safe with this method? Should I put the aerator all the way to the bottom?
Hmmm, seems like I asked more than one question ;o)

To summarize:
1) Would this particular air pump kit work for me?
2) Is it safe to use in a 2' deep pond (20x12' wide) in zone 5?
3) Should I put the airstone on the bottom of the pond if it is just 2' deep?

Thanks again for such an informative article!
Merry Christmas to you and all your readers :o)

12. Posted on December 17th, 2010 at 8:39 am.

By Rafe.



I attempted to connect to the link and there was not an air pump there for me to evaluate. Sorry. I do recommend a Luft air pump <http://www.thatpetplace.com/pet/group/10427/product.web>http://www.thatpetplace.com/pet/group/10427/product.web . It is high pressure and it is heavy duty for your purposes. This is the air pump I use on all my ponds and client's ponds. In critical situations where the air pump cannot be checked every day, I would use two air pumps in case something happens to the air line or the pump itself. You do not want situations where there is no air pumping for more than a couple of days in the middle of winter -- so if you cannot check then use two pumps. I check my ponds every day 365 days a year.

Yes, it is safe to overwinter Koi in that zone at 2 feet. However, it is better for the Koi to be kept at deeper depths for the development of the Koi swimming muscles. The depth allows them to go vertically in a pond. Eventually, you will want a deeper pond for that reason. However, you do not need that depth for overwintering. Remember, like I mentioned in the article, you need to have "most" of the organic matter out of the pond before ice-up. That is all the leaves and debris that may have blown in, needs to be removed or kept out.

Place the air line in the center of the pond on the bottom. You will not supercool the pond.

Have fun water gardening and keeping Koi. Jamie

13. Posted on December 21st, 2010 at 9:07 am.

By Jamie Beyer of Midwest Waterscapes.


Hi, thank you for your article. I am particularly interested in the 'dead zones' vegetation and water circulation factors. Here in the UK we have so far experienced a harsher than normal winter. Not much by certain US standards I would guess but still approx 22-32F outside air temp for past 3 weeks. I have today discovered my 30inch ochiba shiguri floating dead below the ice. My question is - was it poor fish management or age related, etc? She appeared unmarked. She was 20lbs in weight. I have the filtration turned off (believing the water disturbance detrimental as the different pumps would mix upper and lower water temps etc meaning a less stable 39F deep below the ice) - I have done this every winter. Only other 2 variables besides a slightly longer freeze (iced over for only 2 weeks) were 1 she didnt spawn this summer or last(was thinking of dystocia) and 2 more extensive vegetation growth across surface area of pond which is still green) - assumed this not to be demanding much O2 as it was winter? Have noticed the other koi higher than normal in the water for the time of year - clustered in one shallow end near the light. Counting the rings on a scale I get 22 years old. She was the biggest koi by about 5lbs in the pond which is 12000gallons. Any help would be much appreciated, and also understand a diagnosis is not exactly easy without even seeing the fish!

14. Posted on December 28th, 2010 at 4:52 pm.

By Jonathan.



I always recommend circulation in a fish pond no matter what time of the year. I do not know how much organic matter that was in the pond at the time of the Koi's death. I am guessing that was some in the pond. The decomposition of organic matter uses a LOT of oxygen which your fish are extremely dependent on. When the surface of the pond is covered with ice combined with no circulation, oxygen is consumed fast. The largest fish die first from lack of O2. There is another factor that is not mentioned much in the literature, that I think is just as important and that is the loss of invertebrates and bacteria in the pond that is even more O2 dependent. Your ecosystem will be compromised by the lack of invertebrates.

I am worried about your remaining fish - get that circulation going ASAP.

Try not overthink the aspect of 39 degree water being on the bottom and circulating the water would disrupt this layer. Read my article about this. You will not supercool a pond as long as you are circulating the water all the time.


15. Posted on December 31st, 2010 at 9:57 am.

By Jamie Beyer of Midwest Waterscapes.


Help! I have a relatively small (600 gallons, 30 inched deep at the deepest point) pond that has done quit well sense I put it in 3 years ago. I have always used a floating heater that has kept a nice open hole in the ice. However, earlier this year the heater stopped working and the pond froze over for about 3 days. I got a new heater and opened up a new hole. We had a recent thaw and the pond opened completely up. I found 2 of my koi floating on top. A 24 incher and an 8 incher. We have about 10 fish in the pond ranging from 4 inches to the 24 incher. My question is could have the short time my pond froze over caused the fish to die? Or do I have a bigger problem? We had no fish die off the first two winters. I live in central Wisconsin and we have had few minus 10 nights already. Thanks for your help.

16. Posted on January 3rd, 2011 at 3:36 pm.

By Tim.



Yes, even three days without any hole in the ice can be lethal to your fish. There are a lot of factors that enter in how fast the oxygen is used up. Size and number of fish/amount of decaying organic matter (leaves etc.) in the water/whether there is any circulation in the pond/how thick the ice is/amount of submerged plants/etc.

I would use the heater along with an air pump (like I mention in my article). You should also remove most of the leaves in late fall (before freeze-up).

As your fish grow in size then the more oxygen that they demand. I have seen many ponderers do exactly what you have been doing for a number of years and their fish get bigger (and also there may be more of them). Then, all of a sudden, one year all fish die even with a hole kept open by a heater. Not enough oxygen can enter the water column just through the hole.  If circulation had been provided than the fish would not have died for them.

Good luck and have fun water gardening and keeping Koi. Jamie

17. Posted on January 7th, 2011 at 10:31 am.

By Jamie Beyer of Midwest Waterscapes.


We have a large pond, about 100 x 100 feet, over six feet deep in the center tapered to about 2 feet at the outside. The bottom is natural clay. I have a variety of fish in this pond, including some very large koi. I do nothing in the winter pertaining to aeration and have never lost a fish.

Connected to the large pond via a 7 foot wide bridge is a smaller circular pond about 30 feet in diamater, about 40 inches deep at the center. Under the bridge I have placed large stones to keep large fish from entering and eating my water lillies which are planted in containers in the small pond. Small fish can get through the stones in the spring and of course, there is an exchange of water with the big pond. This whole system is fed by a trickle spring and there is an over flow pipe. I have never used aeration.

My problem is this. For the past serveral seasons ALL fish in the small pond have died. What do you think is the cause?
The ponds were built almost 40 years ago and there was never a fish kill untel the last 3 or 4 years. HELP

18. Posted on August 8th, 2011 at 6:17 pm.

By ewald of proud pond owner.


I am not sure the severity of the winter where this ponderer is from but I can say with certainty that there was a lack of oxygen without knowing many details – like thickness of ice.

Most of our ponds build up organic load. This pertains to the amount of un-decomposed organic matter as well as number of fish in the body of water. A pond can go through a number of years without any fish loss then start losing them. I would venture an educated guess that the amount of un-decomposed organic matter in the bottom of the pond is high.  The pond may also be receiving some sediment from the surrounding landscape. Adding aeration is one of the answers. Removing the organics is another. I would do both if possible. 

Jamie Beyer
Midwest Waterscapes 
Work/Cell 515/231-0215

19. Posted on August 17th, 2011 at 3:55 pm.

By Jamie Beyer of Midwest Waterscapes.


Jamie, You mentioned putting an aerator in a 5 gallon bucket with a lid.I have done the same thing but assumed I'd needed to punch small holes in the bucket to allow air otherwise the bucket would be air tight. Without doing so would the pump work properly?
Also, I live in Zone 5. Would covering a pond that is 6' x 10' and only 20" deep with a clear plastic " tent" allow me to over winter 2 -8" Koi and 4 Shubunkins. I do use an aerator with 4 long airstones. 1 long side of the EPDM lined pond is against a paved driveway with an additional 2 feet high x 3' deep garden bed above that. I was planning on tenting the pond and garden bed.
Does this sound like a plan that could work? I like the idea of the fish being able to hibernate over the winter in the pond.
Lastly, would cutting my pond plants back and leaving them in the pond at the depth they are used ,cause wintering fish and the pond's bio system more complications?
I'll very much appreciate your opinion.

20. Posted on August 27th, 2011 at 7:17 pm.

By Tim.



A person needs to cut a hole big enough to allow the cord and air line out the bottom of the bucket. This hole allows the air exchange you mention. I like to set the air pump on an old wash cloth to close the hole some (prevents snow from blowing into the bucket) and reduce the vibration of the pump..

The tent idea works very well. Personally I do not do this but I make sure that I have 99% of the organic matter out of the pond and that my aeration is working 24/7 – without fail.

As long as your plants are marginal hardy types they should do fine. Water lilys and lotus (which are not marginal plants) cannot have ice reach the tubers. Cattails will die if the tops are cut back below the water line. Just leave the tops above the water level.

Have fun water gardening. Jamie 

21. Posted on August 30th, 2011 at 9:19 am.

By Jamie Beyer of Midwest Waterscapes.


I lived in northern New Mexico for a number of years, never had a problem from the ice. I tried a number of approaches: leaving filters and waterfalls running constantly, bubblers, visqueen tent. All worked just as well. Never lost a fish, and the ice would get better than a foot thick at times.

The best approach? Move somewhere you don't get ice. I'm in north FLA now; winters get down to the teens at night, but never long enough to create ice. Fish thrive from the seasonal change, but no icejams to worry about. But don't everyone come all at once, eh?

22. Posted on August 31st, 2011 at 8:23 am.

By Moai Mike of EXPEDITIONS.


Your october 2009 article was really great thanks for the help and guidance. What size air stone and mfg are You using ?
I have a 4000 gal pond that that is oblong that is 6' deep in the center have 8-9 12'-24" koi and a 20 small 4" koi.
I live in Conn. north west conner and experience winter conditions what seem to be similar to yours. ice starts around 1st 2nd week of Dec. gone end of march. freeze over heavy snow in winter. your pictures look like my pond.
I want to go with the two pump plan that you use makes sense.


23. Posted on October 21st, 2011 at 6:19 pm.

By Tony.



I use an all weather pump called a Luft Pump. It is a relatively small pump (from the standpoint of outdoor pumps) but is dependable and has a rheostat on it. I usually have the rheostat turned fully on. The link to the pump is http://www.thatpetplace.com/pet/prod/209767/product.web

A lot of ponderers would think that this is too small of a pump but I have found that it works wonders in keeping a hole in the ice but does not cause huge water currents that the fish have to swim in.

I simply weigh the end of a piece of air line tubing without an airstone. Placed in the center of the pond.  I like a good slow circulation.

Two air pumps are a good idea.

Do not let the snow or moisture get to the pump's intake. This will cause the air line to freeze up easily. If this does occur it is simply a matter of replacing the air line. Inexpensive to do.

I like to place the pumps in a bucket with a lid like I say in the article. I have since been placing a washcloth under the pump to prevent snow from blowing into the bucket (through the hole that you need to get the air line out and cord). Since I have been doing this it is rare for my air line to freeze up.

Go by the article in checking on the pumps every day. Do NOT let them fail. It will sure be deadly to let them fail.

24. Posted on October 28th, 2011 at 3:30 pm.

By Jamie Beyer of Midwest Waterscapes .


I have a concrete koi pond that is an L shape. The pond measures 19' one side of the L, 13 feet the other side of the L and 7 feet wide, by 3 feet deep. A water fall enters the pond at the inside of the L corner. The water fall drops from a 15 foot long stream to a drop above the water of 2 feet. There is a skimmer on one end of the L and a filtration system at the top of the hill. I am wondering if I need additional aeration and if so, what would you advise.
Thank you so much for any advice you can give. Joyce

25. Posted on March 30th, 2012 at 7:23 pm.

By Joyce Bickel.


Jamie I loved the article I really did but I know a lady who would agree with everthing you've said here but then tell you tales of -24c with windchills of -54c with her own pond in Canada


26. Posted on April 25th, 2012 at 12:08 am.

By Dave.


I have a 3000gallon pond 5 feet deep with lotus and water lilies in zone 5 which I will place their containers on the bottom of the pond over winters. First question:Is the organic matter from the dying leaves a problem to my fish and secondly, with this deep of a pond how do you recommend removing organic matter from the pond bottom. Thanks and the article and following comments answers were great

27. Posted on August 7th, 2012 at 5:17 am.

By greg shoukimas.


If you do not have a bottom drain there are companies that sell pond vacuums - one example is http://muckvacdirect.com/. There are also natural bacteria that can be added. It is good to keep be bottom free of organic material as it can rout and release toxins in the water. You probably know this, but before placing the lilies and lotus on the bottom you can trim off the leaves. Thank you for your question and comments.

28. Posted on August 16th, 2012 at 10:17 am.

By Cindy of POND Trade Magazine.


Mr. Beyer,

I was very interested in your article. I live in Canada where the weather varies from +30C in a hot summer to -30C in a cold winter. I was thinking of burying in a 300 gallon stock tank as a pond and was wondering if, using a heater and or/ aeration, I could get away with leaving goldfish in over the winter. The stock tank I am thinking of (Rubbermaid) is only about 26" deep. Growing up in England, my parents had a concrete pond @ 4' deep and my father would simply drain a little of the water out and leave a gap between the ice and the water, but obviously our winters there were not as severe as they are here. I'm not averse to a bigger, deeper pond if necessary, but I'm not sure of a source for "unfancy" ponds. Any advice would be welcome.

Many thanks, Louise

29. Posted on October 25th, 2012 at 10:47 am.

By Louise.


Supplemental heat is going to be necessary for that size of pond along with some aeration.  Not much aeration -- just a stream of bubbles rising from the center and on the bottom of your pond.  Too much aeration will cause your fish to fight a current.

It is going to be expensive for the supplemental heat -- $40 to $50/month (or more) for a 1500 watt floating stock tank heater.  This depends on the severity of the winter.  This size heater is what I think would be necessary.  It is possible to go with a smaller heater but it would be a risk depending on the winter.

If it were me, I would get a 100 gallon Rubbermaid stock tank to put the fish into and keep in a basement or other cool spot.  Cooler the better as long as it does not freeze.  If the temps can be kept 50 degrees or cooler then feeding and water changes are not necessary.  You did not mention how many fish but if you are keeping them in a 300 gallon tank then there can't be many I am assuming.  If you have any more than 10 - 6 to 8 inch fish, then you would need a bigger stock tank than 100 gallons.  Of course, you aerate the indoor stock tank as well.

The technique of your father to create a gap between the ice and the surface of the water is interesting and one that I have tried.  Problem is the weight of snow can collapse the ice depending on the thickness of the ice as well as the amount of snow.  I think in certain situations this would work but not were you are at -- as you know.

If you had a larger and deeper pond then I would just use aeration for overwintering outside.  Using EPDM lliner to create a bigger pond would be a good choice for you. Minus 30 C is a cold I have a lot of experience with.  Go with a minimum 2.5 foot deep pond that is at least 1000 gallons and that would work with just aeration.

Good luck Louise and have fun ponding.  Jamie   

Jamie Beyer
Midwest Waterscapes 
269 U Ave.
Boone, Ia  50036
Home 515/433-0194
Work/Cell 515/231-0215

30. Posted on October 28th, 2012 at 2:42 pm.

By Jamie Beyer of Midwest Waterscapes .


Hello I'm from Canada. WE have been told the ONLY way to overwinter koi/goldfish is a water pump at the surface and a surface heater. This way the bottom layer below the frost layer will remain warmer up to 39F. I did try this and it works. However this winter I decided to aerate and actually measure the water temp. The water temp is 32.7F top and bottom. I did not measure in the past the water temp using surface water pump.

Question is are you 100% certain that the surface pump method will not warm the bottom layer?


31. Posted on October 30th, 2012 at 5:49 pm.

By walter.



Yes, the bottom of your pond will get to 32.5°F if you aerate (or circulate with a water pump). Place the airstone in the center and on the bottom. I prefer aeration over a water pump. With an aerator you still are oxygenating the water under the ice dome that develops without supplemental heat. This cold of temperature will not harm your hardy fish. The fish need to go into winter healthy and there cannot be any decomposing organic matter (leaves) in the pond.

I used to use supplemental heat but discontinued using it. I realized it was a waste of energy (and money) as long as you have an in-ground pond that is 2.5 feet deep and greater than 1000 gallons.

If you would have measured the pond temps at the bottom of the pond when you were circulating with a water pump – I would bet that they were 32.5°F. Yes, all the experts say the bottom will be 39°F which it is when the ice first forms but as winter progresses those temps fall with the winters that we have and thicker ice forms.

Walter, I also have gone down that road 25 years ago and believed all the experts. I have since become an expert that has been successfully overwintering Koi and hardy goldfish for myself and my clients where it gets very, very cold. There are a lot of variables when it comes to water gardening and keeping fish outside. Some are obvious and some are not. I cannot say for certain that your fish will be fine until I have a lot more information from you about your pond. I know that my own very large expensive collection of Koi (about 40 of them) and very large and valuable Calico Shubunkins (92 of them I keep outside year-round) are extremely healthy. I would not jeopardize them in any way. Please carefully read my article on "Overwintering Koi Under Thick Ice."

What is important Walter, is for you to use what has worked for you in the past. I do not want for you to feel like you are making a mistake by believing me. You have to have confidence in the techniques you are using. Stayed tuned for another article by me in a few months in Pond Trade. I truly believe it is up to me to get a lot more information out to ponderers that want to keep Koi and hardy goldfish outside where it really gets cold.


32. Posted on November 14th, 2012 at 4:50 pm.

By Jamie Beyer of Midwest Waterscapes.


Thank you Jamie for the reply and info.

I have decided to do aeration at 1ft deep and with a heater on the bottom. I have a temp probe line at bottom and it reads 36.4 now. I just wanted to get the temps warmer at the bottom. looks like it's working.

Outside temp is 20F and is now complete ice cover except for a 6 inch hole at aeration spot.


33. Posted on November 17th, 2012 at 5:10 pm.

By walter.


I have had no problem with my koi pond over the winters for more than 5 years. I have two friends who also have koi ponds. The other day one of them said that he used a hammer to open the ice over the pond because he was told that his fish must have exposure to light. Oddly, I have heard that you should NOT hammer or pound on the ice and have heard nothing about opening up the ice so that the fish can be exposed to light. This makes no sense to me and I have never worried about it before. Is there any need to assure that fish have exposure to light during the winter?

34. Posted on February 1st, 2013 at 9:01 am.

By Mark of none.


My concern is the problem of TOO MUCH air. I bought the size air pump recommended for my pond but I see that it is kind of a "rolling boil" as you mentioned. Is there anything I can do to calm it down without having to purchase another expensive piece of equipment?

35. Posted on February 9th, 2013 at 12:54 pm.

By phyllis daniels.


Some air pumps have a rheostat on the pump and can be turned down easily. For those pumps without this, it is easy to put a valve on the outlet tubing of the air pump and bleed off any excess air.

36. Posted on February 13th, 2013 at 8:42 am.

By Jamie Beyer of Midwest Waterscapes.


The fish do not need any exposure to light nor do the plants. Yes, plants and algae will give off some oxygen when exposed to light. When there is ice on the pond, there is normally not enough algae and plant leaf to have much photosynthesis going on. Aeration is the key to adding oxygen. Plants will survive without light as long as they are in cold water and dormant. Good question by the way.

37. Posted on February 13th, 2013 at 8:49 am.

By Jamie Beyer of Midwest Waterscapes.


That's the beauty of fish in the winter, ok you cant fully enjoy them as much, especially for an outdoor pond, but on the flip side, they require practically zero maintenance as they hibernate - no feeding, and no water changes.

The only thing you have to make sure is that there are holes in the frozen ice at teh top of the water, if not you risk suffocation with no oxygen getting in there.

38. Posted on March 27th, 2013 at 8:23 am.

By Steve Doyle of Aqualife2u.


Jamie, I enjoyed your article. We have a 200 gallon preformed pond with 2 small koi (3-6"). We live north of Chicago near Wi state line. The pond is 18" deep and was originally just a water feature, however we added koi this year. Is an 18"pond deep enough to overwinter with a deicer and aerator?

39. Posted on September 2nd, 2013 at 7:32 am.

By Phil.


Hi, Great article but of course I have questions. I have a fairly large pond, approx 35x25 by 2 foot deep (it is irregular shaped) and I am guessing it holds 12,000 to 13,000 gallons of water. Would one air pump be enough or should I have two or more? I was looking at the large aerators on Drs. Fosters ans Smiths website for ponds up to 12,000 gallons but it seems they would be creating move water movement that this small pump. Which option do you feel would be better? Last year was hard with the snow cover we had and I lost quite a few fish as I was only using a pump to move water at the surface. I don't want to have the same thing happen again. Thanks for any advice you may have.

40. Posted on September 7th, 2013 at 8:03 am.

By Pam Bradley.


You can overwinter your Koi in a pond of only 200 gallons provided that you do add the floating deicer of 1500 watts or greater. Aeration must also be provided. The pond needs to be entirely in-ground. The ground provides a heat source and serves as an insulator for the water garden. Ponds that are deeper and has more volume can get by without the supplemental heat in your weather zone as long as you provide the aeration that I mentioned in the article.

Another important aspect is that the organic matter (leaves etc.) are removed before ice forms. This organic matter uses precious oxygen in the decomposition process.

The downside is the cost of providing this much heat with a 1500 watt heater. $50/month is an approximate amount that it takes -- depending on your cost of electricity.

A lot of ponderers will bring the fish inside with this small of a pond to overwinter them to save the electricity cost. Have fun ponding.
- Jamie

41. Posted on September 8th, 2013 at 7:30 pm.

By Jamie Beyer of Midwest Waterscapes.


I have a 6000 gallon koi pond with a large waterfall, a couple water lilies and another unknown plant, which came with my house. The deep section is probably 3'x18' and 38" deep. There is another (water pump) submerged in a 15" deep area that the previous owner said ran through the winter and provided enough oxygen for the fish. Would it make more sense to not run that pump and just run the luft pump you mention with the outlet at the deepest point? Also, OT I suppose, could I run the airator and small pump in warmer weather overnight or do you recommend running the waterfall 24x7 in warm weather?

42. Posted on September 24th, 2013 at 8:32 am.

By Chris of na.


Hi Chris.
Water pumps running through the winter cause three concerns for me. I would worry about the intake of the submerged water pump plugging in the middle of the winter - I can be difficult to get to under the ice. Another concern is the stream/waterfall that the water pump supplies, icing up and overflowing the sides. Most of the pond's volume can be pumped out in very short amount of time. The final concern is the electrical cost associated with running a water pump which can be quite high. Since the previous owner had run this pump through winters, the first two concerns may not be much of a problem. However, the electrical cost is still there.

Only 15 inches of depth is fairly shallow for the zone I live in (zone 5). Ice easily gets that thick here. If you live in a warmer zone than this depth may be enough so that ice does not get too thick.

Because of the above concerns I like to use an air pump instead of a water pump. It is critical that this air pump does not fail so it needs to be checked every day. If you can not check it every day then I would set up two air pumps. An extra one in case one of them fails, for whatever reason.

It is always recommended to run the waterfall 24/7 with a water garden or fish pond in warmer weather. The addition of an air pump in the summer is also a good idea.

43. Posted on October 11th, 2013 at 7:11 am.

By Jamie Beyer of Midwest Landscapes.


Hi Pam.
Nice size pond and yes, one of those small air pumps would not be enough. I would add at least one more and maybe two more. You mention that the pond is irregular in shape. I have seen ponds that are so irregular that they could have an anoxic zone (without oxygen) in part of the pond.

If the fish venture into this area they can succumb to the low oxygen and not be able to escape. The solution is to have aeration in all parts of the irregular pond. Make sure that you have all the air outlets on the bottom of the pond which creates good circulation throughout the water column.

I do like more than one air pump for an additional reason -- that being if one fails you still have the other one(s) working.

44. Posted on October 11th, 2013 at 7:14 am.

By Jamie Beyer of Midwest Landscapes.


Thanks Jessica!
So glad that you are enjoying the magazine and you find it helpful.
- Lora Lee

45. Posted on October 17th, 2013 at 12:20 pm.

By Lora Lee Gelles of POND Trade magazine.


Hi Jamie, I'm so glad I found your article. I live in central Minnesota. I had a 4x8, 18" deep, 300 gallon pond the last two years and brought my fish inside for the winter. This year I made the pond larger, it is now 10x17, 32" deep, and 2500 gallons. (The pond has ledges, the first ledge is at 12", the second is at 24", and then the bottom of the pond is at 32"). I kept up with weekly pond maintenance; adding beneficial bacteria, using barley bales to reduce algae, and doing weekly 10% water changes. Towards the end of September I ran out of SAB Pond Clean (String Algae Blaster). Two weeks went by without adding the SAB and the string algae just exploded in growth and now I can't get rid of it! I know that your recommend removing as much organic debris as possible. I have removed virtually every leaf possible but the string algae is nearly impossible. I can still see the rocks on the bottom of the pond and I did remove as much of the big clumps that I can but there is still a lot of the fine hairy growth stuck to the boulders and on some of the shallower rocks. How do I get rid of it?! And will it consume too much of the oxygen for the fish. I only have 3 koi and 2 Sarasa each approx. 6-8". I plan to add the Luft air pump you recommended. This will be my first year wintering the fish in the pond. Will they instinctively know what to do because they have been brought indoors the last two years and didn't get a chance to hibernate? I am just so worried about them. Also, a pond expert helped me break down my pond for the winter; removing plants and turning off the two waterfalls, but, to keep an opening near the waters edge, he left one of the water pumps in the skimmer running to push water thru a "winter bypass" that shoots water up towards the surface. The distance between the skimmer and the bypass are about 18". I just hope it doesn't freeze. Is that enough water movement to What are your thoughts on that? should I chance it or use an air pump? Thanks for any advice you can give!
Cindy Nowitzke

46. Posted on November 14th, 2013 at 8:36 pm.

By Cindy Nowitzke.


Grrr. I meant to hit the Preview button. I see there is editing that needed to be done...

I meant to ask: Does the winter bypass provide enough water movement to keep a small area from freezing, provide oxygen for the fish, and an outlet for the poisonous gasses?

47. Posted on November 14th, 2013 at 8:45 pm.

By Cindy Nowitzke.


The string algae will not be a problem for overwintering your fish. As a matter of fact the algae serves a filter (phytofilter) and will benefit the fish even during the winter. If you were to try and kill it now could be lethal to your fish due to decomposing string algae.

The fish will survive fine even though they have not gone through a winter outdoors. These fish have evolved in conditions like we have and actually need a cold spell for them to really thrive. Maybe not as cold as we get but they do need a cold period. They will be fine.

I am not understanding completely your arrangement of moving water but I always use an air pump with the air outlet in the center of the pond. I do not see a problem the way I am understanding your water pump set-up but it sounds like it is at the edge of your pond. You definitely need the circulation in the center.

Have faith but make sure you adhere to all the details of my article.

Have fun ponding.

48. Posted on November 28th, 2013 at 1:25 pm.

By Jamie Beyer of Midwest Waterscapes.


GREAT article Jamie!!!
Thank you!!

49. Posted on January 31st, 2014 at 10:26 am.

By Kelly Billing of Maryland Aquatic Nurseries.


Jamie, Thank you for this wonderful article! We heard you speak this past Sunday in St Paul (in fact, I won one of your Voodoo Lily bulbs!) and then came home and looked for more wisdom from you online. We are SO happy to have located this very informative and thorough article. Thank you for all your time and effort in helping out us pond owners/koi lovers. Thank you as well for your research in getting to the bottom of this "super cooled water" debate. Btw, based on your extensive experience/success, we are changing our "method,"... Luft pump ordered this morning! Now, for more info on your bog water cleaning method. Any articles on that?
7,000+ gallon pond -all for the enjoyment of one little 8" koi "Freddie" and his buddies

50. Posted on April 15th, 2014 at 11:02 am.

By Jody.


I had a great time this last weekend in Minneapolis. The Minnesota Water Garden Society really knows how to conduct their meetings and treat their presenters.

The "bog water cleaning method" that you mention has been written about as a fairly common method of filtering fish ponds. I have not written anything on the subject but many authors have. It is great way to add biological filtration that has very little maintenance. The maintenance depends on how well it is designed. Good luck with your pond Jody. Hope to see you soon again. Maybe you guys will invite me back.


51. Posted on April 18th, 2014 at 6:54 am.

By Jamie Beyer of Midwest Waterscapes.


We sometimes get 50 below 0 in Wisconsin. If that ok for the fish, how deep should I make my pond?

Thank you

52. Posted on May 8th, 2014 at 5:18 pm.

By Lori.


A section of your pond that is 48 inches would be good. Add aeration at that point year round. You could go 36 inches but that is more risky. It needs to be an in-ground pond. The 4 foot depth needs to be over a majority of the pond. Planting shelves of 12 inch depths are always a good idea for access to your pond as well as a good place for plants. Jamie

53. Posted on May 20th, 2014 at 8:49 pm.

By Jamie Beyer of Midwest Waterscapes.


I have a 270 gallon pond and was wondering if I can winter my koi in it and if so, how to do it. It is 18 inches deep. I live in east central Wisconsin.

54. Posted on September 13th, 2014 at 5:40 am.

By Kathy.


Jamie...THANK YOU for your article on Overwintering Koi..First winter coming up and have purchased a Pondmaster Deep Water Air Pump...5/8ths tubing...

My 2 ?'s are: Do I use an air stone/diffuser or leave the end of the air line open for large bubbles to be produced...???...

If an air stone/diffuser is to be used what type do your recommend...???...


55. Posted on September 16th, 2014 at 6:11 am.

By Larry.


Go ahead and use a air stone/diffuser with that type of pump. Get one that is heavy enough to hold the end of the air line to the bottom. I have no preference as to the brand or style.

56. Posted on October 13th, 2014 at 7:42 pm.

By Jamie Beyer of Midwest Waterscapes.


This is a small enough pond that I would add supplemental heat or bring the fish indoors. Please read my Overwintering Pond Fish Indoors article.

57. Posted on October 13th, 2014 at 7:44 pm.

By Jamie Beyer of Midwest Waterscapes.

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