How to Maintain Water Quality in Recreational Ponds

Published on April 27, 2023

how to maintain water quality in recreational ponds
Aerial view of the “No Passport Required” plunge pond.

Let me begin by stating what this article is not going to cover — a biology lesson and municipal codes. What it will cover is how to maintain water quality in recreational ponds.

Following major back surgery in 2008, I was fortunate and healthy enough to pursue my latest passion in my life. For the next couple of years, my company, Liquid Designz, was back to constructing water features. We couldn’t be happier.

Aqua Ultraviolet

That being said, however, we weren’t at the point where we were installing recreational and plunge ponds. In fact, I barely knew what the heck they were about. Nor did I understand the importance of water quality and its very distinct difference from water clarity. I had picked up a few pointers along the way from countless seminars (along with some Anthony Archer-Wills reading material). However, the majority of my knowledge and interest was in the construction department. And the questions I used to ask along the way? Just ask Ed and Brian at Aquascape, as I’m sure they remember all too well.

In 2012, our “No Passport Required” project came about and was featured in the May/June 2013 issue of POND Trade magazine. It was constructed at our showroom in Bergen County, New Jersey. It was a fun event, as I invited a few contractors as well as CAT, who donated two machines. I felt that this would be an ideal location to learn and experiment.

Due to the existing steep hillside and old railroad tie wall, I knew that containing and redirecting as much run-off as possible would be a crucial and constant challenge. We began by incorporating some of the basic necessities that most recreational ponds should have such as a wetland filter, aeration, multi level jets, etc. We also implemented some of our own methods with the initial construction. The design has since changed dramatically over the years, as my newfound passion — achieving the healthiest water quality possible — has arrived and remained at the forefront.

The Role of Sand

wetland filter
A main wetland filter is constructed within the stream area.

Since we were planning to install a beautiful beach adjacent to the design, I figured we would begin with a sandy bottom, which made perfect sense to my distorted mind. This decision had now taken me into uncharted territory. We had also implemented a nice fish load the first three to four years. Eventually we began to shift gears and designed a couple of new floors. However, not before gaining invaluable knowledge about the use of sand within a water feature.

This didn’t occur just by distributing some sand at our showroom. In fact, it got very interesting as far back as 2009. Located very close to our showroom is a very affluent area with a natural swimming vessel known as Graydon Pool. It has a lovely, natural sandy bottom and spring-fed swimming pool area on 2 ½ acres that has been a staple in the community for what seems like forever.

Unfortunately, there was a drowning that year. The bigger problem was that the lifeguards on duty couldn’t locate the young man for 30 minutes or so due to the cloudiness of the sandy water. Following the incident, the town council had multiple meetings while seriously entertaining a design that Liquid Designz and Perrone Ponds. Unfortunately, they decided to keep things as they were.

However, there was some good that came out of this situation. I became friendly with one of the higher-up staff who was responsible for all aspects of maintaining Graydon Pool. This included learning about the type of sand they had finally settled on (triple rinsed) and how they maintained it. He informed me that an estimated 300 tandems of this fine white luxury are dredged out of a few specific areas along the New Jersey shore and trucked up the lovely New Jersey Turnpike every season.

Did you catch that? The old sand is dredged out each season, and new sand is brought in. This is a must when implementing sand within your water feature, regardless of what zone you’re in. Any idea where we obtained our sand every season? You guessed it, and it was complimentary as well. We also learned how the pool, which bordered and drained somewhat into the wetland area, was approved to use a very low dosage of chlorine each day . This was closely monitored by the U.S. Environmental Protection Agency (EPA). Due to the small draining weir that led into the large wetland area, an exorbitant amount wouldn’t be acceptable.

Some Interesting Feedback

So when the article came out in 2013, it had a picture of my son enjoying the water of our newly designed “Plunge/Rec Pond.” It was Liquid Designz’s first real exposure. As I began to read some of the responses to the article, some comments and concerns took me by surprise.

Remember, I was a rookie taking on a pretty unique design for the first time. Most of the comments, however, were very favorable, which was nice to see. I remember one in particular from Dave Kelly. The criticism, for lack of a better word was due to the question, “How did I know that the water quality would be safe for human interaction?” It certainly was a fair question, and one that every contractor should be concerned with when constructing recreational ponds.

A couple of readers pointed out their concern about a bacterial infection known as necrotizing fasciitis, which occurs when stagnant or unhealthy dirty water filled with bacteria comes in contact with an open wound. It sure sounded like I needed to educate myself once again, as my desire for this industry seems to have me committed for a while!

It was from that point on that our showroom transformed into our own Dr. Frankenstein lab, if you will. I love construction as much as the next guy, but there’s only so many cool water features one can build, demo and then rebuild. Since then, our main focus has always been on how Liquid Designz could achieve the healthiest water quality possible.

It has been so rewarding over the years to see all the different styles of recreational and plunge ponds installed. There is an abundance of talented contractors in our industry, and I’m glad to be a part of that group. I have worked with many of them and have shared countless correspondence with some of them throughout the years. There is nothing I enjoy more than helping others while gaining knowledge from them as well.

Water Testing

Water quality testing equipment
Testing equipment (left inset) should include total coliform count, E. coli tester and total dissolved solids meter.

For the first four years, all our testing was done through an established lab. Of those eight test results (twice a season back then), one test showed a positive coliform/E. coli count. I actually remember the week of the test. We had a few flocks of starlings enjoying our design every day. It wasn’t a big deal, since we knew we had the correct filtration in place, and any trace should filter out sooner than later.

I still keep in touch with the lab rep who used to come out and grab the samples. I’ll never forget what he said when we spoke after the very first test was administered. He told me that the lab technician didn’t believe we didn’t have a UV light installed. The water was as close to potable as you could get, especially for these types of natural designs. (That being said, I still feel that a UV light is a great addition under certain circumstances.)

One of my favorite tests is to see how quickly our design works through a heavy rain event, both for water quality and clarity. The location of our design is ideal for this. Our plunge-pond design was constructed in the middle of an existing patio and steep hillside. Though we did what we could to keep runoff to a minimum, it still occurs during heavy rains. However, in our case, it also would bring some of the beach into the water as well. It’s difficult enough keeping the anaerobic buildup beneath the sand to a minimum without this occurring.

All these factors created an excellent opportunity for testing via different means and methods. We test directly after, as well as a couple of days later. This will typically depend on the size of your particular design. One of the things I do during and after a heavy rain event is slow down both of our pumps. The other crucial test is to gauge the phosphorus/phosphate count. Though essential for our plants and other aquatic life, an excessive amount could lead to low levels of dissolved oxygen, which in turn affects water quality.

The Splash Pad

Right next to our main feature at the time was an rainwater-fed splash pad that had very little filtration. This was done purposefully. (There is always a method to my madness.) We did, however, have constant water movement along with some of our unique filter media that we placed in the first flush filter, filling up the inside of the 300-micron net. It was still a fun place to enjoy during the hot summer days, so we wanted water with acceptable quality running through it. Once in a while I would throw in an occasional small chlorine tablet just to be on the safer side.

ceramic structural aggregate and sunshelf wetland filter
Our tri-blend of ceramic, structural and lightweight aggregate (left) was implemented into our “sun shelf” wetland filter (above).

The cool thing is, for the five years or so that we had the splash pad, it was tested every single time our main swim pond feature was. Can you guess the test results? If you guessed positive every time, you would be correct. So, here we had the same environment, location, wildlife, aeration and runoff as the adjacent feature, but with contrasting results. This wasn’t a shock to us, as we understood that without implementing the standard methods of filtration along with our additional filtration methods and materials, these contrasting results were not surprising.

Fast forward to the 2022 winter/spring months when I decided to rip out that same very cool splash pad, which wasn’t too popular a decision among my family and Ryan, the foreman. Once again, there were two specific reasons why I did this. One, I was bored with the splash pad. Two, I wanted to construct something truly unique to enjoy and to equip me with another body of water to work with — a sun shelf and reflection pool that would be naturally filtered by its own wetland filter, as well as many other methods. The design would not only be an awesome place to hang out and cool off, but more importantly, it would also serve as another vessel to test and hopefully confirm the same results that the main feature design had returned since 2014.

As I expected, our most recent design did bring back the same exciting water quality results that we had been accustomed to. I can confidently say that we are definitely on the right track and will continue to grow and educate ourselves. In the meantime, as much as we would like to install more recreational and plunge ponds, the reality is that we have assisted and bid on a number of them. To date, we feel quite fortunate to have a couple of beautiful and unique designs to continue our ongoing testing.

Keys to Filtration

The testing kits we use are both for drinking and well water using EPA-approved quality standards. Shoot for the stars is my philosophy. Every three weeks, unless there’s a heavy rain event) we implement the following tests: coliform/E-coli, volatile organic compounds, dissolved oxygen levels, total dissolved solids, nitrates, phosphates, lead and copper.

One of the other important aspects of filtration is how often you turn over the volume of water from your design. This is very different from how quickly, or I should say, how slowly water should flow through your particular wetland filter. I haven’t come up with a firm, consistent test number that has altered the filtration either way.

construcion of a recreational pond
In-progress construction photos are shown of the vanishing-edge filtration area (top left) and bubbling beach boulder (bottom left) bog area filter. The completed vanishing-edge area (above) turned out great. The red arrow indicates the return from the beach bog boulder.

Filtration or regeneration zones, according to many, work best when they comprise 50% of the total square footage of your bathing vessel. Our designs that I speak of here are approximately 40%. Obviously, it’s much easier to pull off a significant filtration area on smaller designs.

We also have spent a fair amount of time over the years trying new floor styles and designs. As indicated earlier, we started with a sandy-bottom design with fish. Then I decided to deepen the design a bit, cutting out a large area of the floor liner to gain a little depth for our new bottom aeration setup. This is crucial to avoiding any stratification.

The problem with sand is being able to implement bottom aeration throughout the majority of the floor area without the water clouding up each time you use the design. I was fine with the latter, but was I set on a brand-new floor idea where one could walk all over the bottom without disturbing any of the five aeration disks — not an easy feat if you have a design that is only 3 to 4 feet deep with constant foot traffic. However, we absolutely accomplished that.

Other Ideas

Some additional methods that we have implemented include moving water from the main vessel to other areas. In our case, a beautiful, bubbling, beach-grade slab surrounded by aquatic plants. It’s that not only is aesthetically cool but functions as our secondary filter. It took some serious juggling to pull this off. One valve controls how much water from the main pond goes sub-beach and connects via bulkhead to create the bubbler. The spillover is then captured by a 360-degree perimeter catch basin loaded with our unique filter media and aquatic plants.

The challenge, however, was positioning the receiving bulkhead from the pond area just above the exiting bulkhead from our bubbling beach slab, which, of course, takes that water via flex under our patio slabs and dumps into our vanishing edge area — the final but very effective filter area. This vanishing edge area is so cool. I’ve done quite a bit of testing with assorted materials over the years in this section, with never any clogging. We use a large, standard filter media cut-to-size pad, another different-density pad, a thick layer of LEED-certified aggregate and some natural smaller beach or standard gravel, which helps to keep the lightweight aggregate in place.

My hope is to see more contractors sharing some of their water-quality test results as well. It is my opinion that when you put a recreational pond title on your design, it takes on an entirely different aspect of contractor responsibility. It’s more than just gorgeous aesthetics. Clectively we can continue to contribute to our amazing industry while gaining a larger share of the swimming pool pie. Always remember that the more your clients enjoy their recreational pond, the healthier they will remain.

Kloubec Koi Farm

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