So how do you build a CrossOver Pond?

Published on March 2, 2010

1_cross_over_pond_water_garden_pondMost pond installation contractors are familiar with water gardens and koi ponds – as they’ve both been around for quite some time now, and both pond styles are very popular. Water garden ponds, in terms of numbers built, are the most common pond type – primarily because of their ease of installation, and natural appearance. Koi ponds are the second most popular pond style – primarily through the influence of koi dealers, koi clubs, koi magazines, and online chat rooms.

Over the years, we’ve found that both designs have some limitations. Water garden ponds are not designed with koi growth and development in mind, and koi ponds are not typically designed to blend into the landscape. A water garden pond becomes part of the landscape while a koi pond is an element within the landscape.

The huge gap between water gardens and koi ponds is what led us to create our Hybrid pond concept back in 2003 – to create healthier environments for koi than provided by water garden ponds.

In a partnership with the Kodama Koi Farm formed in 2004, Russell Watergardens & Koi committed to improving pond conditions for koi and ease of maintenance for pond owners. The Russell Technologies CrossOver Pond is the result of this collaborative effort.

What is a CrossOver Pond?

In simple terms a CrossOver Pond is a pond design that is a cross between a Hybrid Pond and a Koi Pond. It is a pond that is designed for growing larger koi than a Hybrid pond, but more natural in appearance than a typical Koi pond.

Koi pond owners understand the importance of waste removal for koi health and growth, but often sacrifice the natural appearance of the pond in favor of koi health. The general public, for the most part, prefers a pond that reminds them of a natural setting – that’s a major reason why water garden ponds vastly out number koi ponds.

Koi ponds are not unattractive; they just usually have more of a formal, water feature or swimming pool like appearance than that of a water garden pond.

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 So as a contractor, what are you to do when a prospective customer says they want to grow koi to “jumbo” status – but they don’t want a pond that resembles a pool in appearance? That’s where the Cross-Over Pond comes in.

There are many methods of building and filtering koi ponds – one can get dizzy trying to decipher information from suppliers and online chat rooms. But the basics of koi ponds are high capacity waste removal from both the surface and bottom of the pond, coupled with added depth. Most koi pond builders agree – deeper is always better. To grow large koi, water depths of 6´ to 12´ or more is recommended.

One thing that all jumbo koi have in common is that they’ve all come from deep ponds and owners that feed them heavily. Koi need deep water in which to grow large and develop a well muscled body. Well fed koi kept in shallow ponds tend to get un-attractive pot bellies. If you’ve ever been to a koi show and had the opportunity to view jumbo koi 30˝ or larger, you’ll understand the importance of pond depth.

Water volume is also a key factor. One way to get the most water volume out of a given space is to eliminate the stair steps on the sides of the pond – in favor of a “straight down” design.

Remember also, what goes into a koi comes back out of the koi. Jumbo koi are jumbo eaters, and because of their jumbo appetites, they are jumbo poopers too – so the filtration system needs to be able to handle the load and be easy to clean on a regular basis.

So how do you build a CrossOver Pond?

CrossOver ponds have a minimum depth of 6´. For scale, we prefer to have at least one dimension of the pond three times the depth – so our 6´ deep CrossOver Pond would have at least one dimension of 18´ or larger. The pond shown here has dimensions of 24´ x 30´.

Where a CrossOver Pond differs from a koi pond is the inclusion of a boulder/plant shelf. Koi ponds most often have vertical sides with some type of capstone around the perimeter and no shelf. The CrossOver Pond features an upper shelf of 8 – 12˝ deep by 1 – 2´ wide for boulders and aquatic plant basket placement. While this makes the CrossOver Pond a little less safe for the koi than a koi pond – it is what gives the CrossOver Pond a more “natural” appearance than a koi pond.

Like the Hybrid pond, having a filter that is easy to clean is critical. Due to the large amount of waste koi produce, any filter will need to be cleaned often, so it must be easy to clean. In our designs we use backwashable waterfall filters, pond skimmers that can be installed remotely, bottom drain(s), a bottom drain pre-filter, submerged aeration, and UV clarification. You have a choice of pumps – centrifugal and/or submersible.

Unlike a Hybrid pond, the CrossOver Pond does not have submerged boulders. Where the Hybrid pond uses boulders on the vertical walls inside the pond to retain the excavation, the CrossOver Pond’s vertical walls are retained behind the liner – like a koi pond.

These vertical walls need to be retained – either with concrete, blocks, or other building materials. In this CrossOver Pond at our Flagship Store we used treated 4˝ x 6˝ timbers bolted together. The treated timbers are easy to bolt together, but they’re not as permanent as concrete or concrete blocks. At our store, we replace our display ponds every couple of years or so, and the timbers make that easier for us.

The pond bottom should be sloped towards the bottom drain(s) at least 1˝ per 10´ to allow fish waste to work its way into the bottom drain. Since we wanted the water at least 6´ deep, we sloped the bottom from 6´ at the farthest edges down to 6´6˝ at the bottom drain. We graded the slope from front to back – the bottom drain is not in the middle of the pond like a koi pond – but at an end like in a swimming pool.

In this design, we’re using submerged aeration to add oxygen to the bottom of the pond and to create water currents towards the drain. The scattering air bubbles on the water surface effectively push debris towards the pond skimmer. The bottom drain draws water and fish waste to the pre-filter through large diameter pipe, 3˝ or 4˝, depending on total flow required.

Once the earth has been retained, and the bottom drain and piping is installed – you can line the pond with your choice of liner, polyurea, or gunite. Since we chose treated timbers as our retaining material, we installed ½˝ thick Styrofoam sheeting under the underlayment to protect the liner from the timbers.

In the configuration we featured at the store, we then installed the backwashable waterfall filters, the filter’s inlet pipe, backflush pipe, and drain pipe. We used the excavated soil to cover the plumbing lines and to backfill around the filters. The backwashable waterfall filters were installed as far away from the remotely installed pond skimmers as possible for maximum water circulation.

The final step is the placement of large accent boulders around the perimeter shelf while leaving room for aquatic plant baskets. Since there is no gravel in a CrossOver Pond, aquatic plants are planted in plastic aquatic baskets. They’re not placed in pots because baskets allow for plant roots to reach out and pull nutrients directly from the water as they grow through the openings of the basket. Interspersing plants and boulders gives a more natural appearance than having a “ring of rocks” around the pond’s perimeter.

This pond design called for two remotely installed pond skimmers and three backwashable waterfall filters. As you’re facing the pond and waterfalls – the skimmer on the left feeds a single waterfall filter on the right, and the skimmer on the right feeds two waterfall filters on the left – creating an “X” current in the pond. The bottom drain is connected to a gravity feed pre-filter to remove the large debris. The water is then pumped through the UV system and returns to the bottom of the pond bottom to push settled waste across the pond towards the bottom drain.

The result is a pond that has design characteristics found in both koi ponds and Hybrid ponds. The pond uses water currents, bottom drains, bottom drain pre-filters, and skimmers to remove waste from the pond. The owner can then simply backwash the filters and empty the pre-filters and skimmers – there is never a need to drain the pond. The pond features beautiful waterfalls, along with boulders and plants that help “naturalize” the pond into the landscape.

Equipment Installed in this CrossOver Pond

• 3 Dolphin Hydro Vortex Filters with HydroFlush Self Cleaning Backwash Systems

• Pelican HydroClean Remotely Installed Pond Skimmer (Right)

• Piper HydroClean Remotely Installed Pond Skimmer (Left)

• HydroSieve-PF Remotely Installed Bottom Drain Pre-Filter

• 2 HydroDrain Bottom Drains

• HydroUV Modular 72 watt UV Clarifier System

• HydroAir HA-4200 Aeration System

• Hydro Dynamax HD-12000 submersible pump (12,000 gph for left waterfalls)

• Hydro Centrimax HC-075 centrifugal pump (5,700 gph for right waterfalls)

• Hydro Centrimax HC-033 centrifugal pump (2,700 gph for bottom drain suction, UV, and submerged circulation jets)

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