The vast majority of ponds built today are “water gardens” where the main focus is beauty and tranquillity in the landscape. Both fish and plants are featured, often with babbling streams and cascading waterfalls. As pond owners become more informed they often wish to add Koi fish because of their unique beauty, growing popularity and engaging personalities. Koi can be great pets for anyone. They beg for food whenever someone nears the pond and may even eat out of your hand. Hundreds of Koi clubs are in existence around the world and the number grows steadily.

The description “Koi ponds” generally refers to ponds designed just-for-Koi. Plants are secondary and may not be used at all. Plants can interfere with the view of Koi and large Koi sometime damage plants just due to their sheer size. Koi can grow to be more than 30-inches long and can live for many decades. Can Koi live and prosper in a watergarden? Absolutely. The watergarden design can incorporate some or all of the features desired for Koi keeping. The watergarden can even be used as an upper pond that feeds and filters the water for the Koi living in the lower pond.

There is no one design that everyone must follow, for a Koi pond, watergarden or advanced watergarden where Koi and plants intermingle. Pond design is dependent on budget, climate, site conditions and the purpose of the pond. Here are a few design guidelines that will help you select the appropriate design for your pond:

WATER GARDEN DESIGN IDEAS

Water depth is usually 24” or less. This is deep enough to overwinter fish in most climates, safer for kids and easier to watergarden. Aquatic plants do not need lots of depth and are harder to care for if planted on raised pedestals that are set out in deep water.

Plants are the main focus and outnumber the fish by a wide margin. Benefit: Plants filter the water and are sometimes the primary filtration when budget is really tight.

Water circulation/pump size: Sometimes water gardens “get-by” with smaller pumps, especially when only a water fountain or 4” wide trickling stream is desired. Larger ponds, however, larger than say 4-ft X 6-ft, however, work MUCH better with larger pumps. Pumps rated between 2,500 and 3,000 gph are our most popular water gardening pump as this pump size creates great skimming, thus lowering pond maintenance. Higher pump flows also make better waterfalls (1,000 gph/ft of width) and do not stop plant growth contrary to popular opinion.

Rocks and gravel protect and hide the liner, provide a base for plantings and help create an ecosystem. They definitely reduce overall pond maintenance, but do not eliminate maintenance completely.

Filtration: It is important to filter the pond water but normally this is accomplished by setting up an ecosystem where fish, plants, and beneficial bacteria live in harmony. Pumps are added as much for waterfalls as filtration. Filter benefit: They lower the workload to maintain a pond, and become even more vital as pond owners add fish or their existing fish grow and have babies. Skimmers and biological filters are common and vary in size and performance depending on budget. UV lights and bottom drains are options.

Seed bacteria: We always recommend Nitrifier bacteria in new ponds to jump start the nitrification process which removes toxic ammonia generated by fish and decaying plant material. Dry “biological clarifier” is added to help maintain the pond’s ecosystem and again, lower maintenance by keeping filters cleaner.

Pond sidewalls are usually shallow at least in some areas to support marginal and bog plants. Benefit: A larger variety of aquatics add beauty and the pond supports birds, frogs and other wildlife better by allowing better water access. Disadvantage: The pond volume may suffer if space is limited and raccoons can enter the pond. Raccoons will not dive for their prey, however, so a deeper, wider pond will solve both of these limitations.

More sunshine is desired to help plant growth. There is no minimum but 2-hours of sunshine is desired to support better lily flowering.

Koi and goldfish can be easily added to a watergarden but additional filtration and pumping capacity is then preferred to handle the extra and usually expanding fish load. Fish introduced with the plants often will not start eating them, especially if the fish are well fed.

If adding Koi to a watergarden, strive to make it as deep as practical to give the fish more growing and exercise room. One section of the pond that is 3-feet deep would be good and four or five feet or even deeper would be better if “jumbo” Koi are desired.

ADVANCED WATER GARDEN

The advanced water garden not only has all the benefits of the basic water garden it is big enough to grow some koi. It has greater depth and holds more water. It is more stable ecologically so the fish are healthier. The addition of a bottom inlet to the skimmer creates a circulation of water flow from the bottom of the pond that complements the skimming action of the skimmer.

Before a basic water garden is installed you should look to see if it can be expanded into an advanced water garden. Almost everyone who puts in a basic water garden will come back a year later and say they wish they could expand it. Putting in the larger pond the first time is more cost effective and involves less labor than doing two ponds.

The advanced water garden has more plants, more fish, more water, better circulation, less maintenance and is a better investment. If you have the space this is the best pond for the money.

KOI POND DESIGN IDEAS

Water depth, as stated earlier, should be deeper to give the fish more exercise and increase pond volume for better fish loading capacity. Four foot and deeper ponds are considered normal for ponds intended primarily for raising and showing Koi. Ponds eight to ten feet deep are not uncommon.

Water circulation/pump size: Koi ponds must have strong water flows to move waste down to the bottom drains, give the fish exercise and move lots of water through the filters. Many water gardens are built with adequate pumps and filters due to the desire to create dramatic waterfalls. In Koi ponds, on the other hand, strong water flows are not an option…they are a must. Side jets of flowing water are recommended. The latest thinking on biological filtration is that stronger flows ARE helpful. Dwell times are not necessarily the determining factor for successful biological filtration.

Filters: Fish are the main focus in Koi ponds as the name implies and therefore filtration is the name of the game. Many hobbyists take great pride in building filtration systems that are true engineering wonders, but they usually occupy space at least 50% of the pond size…if not more. Most first-time pond installers are not interested in costly or space hungry filters. The good news is that very good Koi ponds can be built with the PSA ecosystem approach and the system takes up little space and is affordable.

PondSweep® skimmers. These filters serve the Koi pond to protect the pump or pump intake if using an external pump. The pump can be located in or near the skimmer to power feed water to the biological filters. Alternatively some Koi keepers prefer to feed their filters by gravity using the PondSweep® to drain the pond and feed biological filters by gravity. The pump is then located downstream of the filters and pumps the water back to the pond via waterfalls or pond jets.

PuriFalls® waterfall filters. These make great biological filters using an upflow design that feeds the water back to the pond via a beautiful waterfall. The waterfalls in turn oxygenate the water. Since they are hidden from view most landscapes can handle this filter type.

UV lights. These are very popular additions to Koi ponds to potentially help with disease control. In water gardens they are not generally needed for green water elimination which the standard PSA ecosystem controls. In Koi ponds, however, where plants and an ecosystem are not featured, a UV becomes more important and useful for both green water and disease/sterilization control.

Bottom drains. Considered essential for Koi ponds. These ponds are deep so the fish have lots of room to exercise. A bottom drain is essential to help circulate the water.

Non-PSA filters. Vortex filters, settling chambers, buoyant-bead or bubble-bead filters can be integrated with the PSA filters as desired to support larger fish populations.

Rocks & Gravel in the Pond: This is a hotly debated topic these days. Many avid Koi keepers are opposed to rocks in the pond. They fear the fish might injure themselves on a sharp edge. They also feel the rocks will lead to anaerobic conditions and the generation of toxic gases. Advocates (like PSA) correctly point out that the rocks and gravel form a huge natural substrate for bacteria, significantly reducing the need for external filters. Benefit: During power outages the pond stays cleaner and safer for the fish. Disadvantage: Even though gravel in the pond works as a biological filter it will probably require cleaning, perhaps once per year in areas with lots of debris. Water gardens can run longer between cleanings, but a lot of Koi in a pond generate more waste and could require once per year cleanings.

Seed bacteria: Just like water gardens, Koi ponds will benefit by the addition of cultured bacteria. These bacteria are used extensively by fish farmers to raise healthier fish in crowded conditions. What better describes a Koi pond?

Pond sidewalls: Since edge plantings are not commonly used, the walls can slope steeply downwards. This provides more water volume and helps protect the fish from raccoons or Herons that might try to perch in the shallows.

Sunshine: I’ve been told that excessive sunshine can bleach Koi colors or can lead to excessive algae. Koi keepers prefer at least some shade.

CONCLUSIONS
Both water gardens and Koi ponds can be built using PSA filters and other pond components. A single pond that meets the needs of both water gardeners and Koi enthusiasts can also be accomplished if the pond is designed at the beginning with Koi in mind, or the water garden portion is simply separated from the Koi pond area.

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