Koi Pond or Water Garden?

Yes, there is a difference. In a water garden the focus is generally on the plants and the overall appearance in the landscape while often keeping a few goldfish as well. With a koi pond the focus is on the koi and proper accommodations should be made. We will now detail each a little more thoroughly.

Water Garden

A water garden can be just about any size. With a water garden you will generally try to establish a balanced ecosystem, or at least as close as we can get when attempting to recreate nature in a closed environment. There are 4 primary keys to this:

1. Plenty of plants. Plant life should be covering 50-75% of the pond surface. This can be accomplished with floating plants like Water Hyacinth and surface plants like water lilies. The typical water garden setup will have an open area around the waterfall and another where the goldfish are fed and viewed. The rest of the pond is usually covered with plant life. Underwater plants like Anacharis are also an important element to balancing the pond. These are placed in the pond bottom and utilize nutrient in the water thereby reducing the available food source for algae.
2. Limited fish load. Trying to keep too many fish is one of the most common causes of pond problems. The fewer fish you keep, the healthier your water garden can be. You can also skip fish altogether and have more of a wildlife pond.
3. Good filtration. Note, I didn't say great filtration. If following the other keys to a balanced water garden, an average filtration system will provide the needed benefits. You certainly can't over filter, so don't skimp on this just for the sake of skimping.
4. Routine Maintenance. By performing small maintenance chores on a regular basis, you will be able to keep a cleaner and healthier water garden, which means you will be able to enjoy it more. As plant foliage decays, remove it so it doesn't become sludge in the pond bottom. If any leaves or other debris from outside the pond finds its way in, remove it. Clean the filter as needed, make sure you do not over-clean. Use packaged bacteria/enzyme products to keep the beneficial bacteria colonies as strong and plentiful as possible.

A water garden should have its total volume being circulated at least once every 2 hours. So, a 1000 gallon pond needs a pump providing no less than 500 GPH.

Koi Pond

A koi pond should be as large as possible. The minimum recommended size for a pond with koi is 1000 gallons and should have an area in it that is at least 3' deep. 4-5' deep is preferred. Unlike goldfish, koi will not stop growing just because they are in a small pond, they will still become large fish. Large fish need plenty of room. Koi ponds also need a much better filtration system than water gardens. The two primary reasons for this are that large fish produce a lot of waste and most large koi eat a lot of plants, which would otherwise be acting as natural filters. The lack of plant life needs to be compensated for with a high quality filtration system. Don't take this to mean that you cannot keep any plants in your koi pond, some may not be eaten. Underwater grasses and floating plants will nearly always be a meal for the koi. Each group of koi is different. Many will also eat water lilies while others may not. Taller perimeter plants are usually safe, but these do not provide the same ecological benefit as the surface growing plants. Another issue when keeping plants with koi is that even if they don't eat the plants they scavenge in the soil of the pot and uproot the plant and makes a mess of the pond. This can be helped by placing cobblestones on top of the pot to keep the koi out.

A koi pond will usually feature an ultraviolet sterilizer to ensure clear water. They will often utilize multiple areas for the water to be pulled from when going to the filters. This may include a skimmer, a bottom drain, and/or a mid-water intake.

A koi pond should have its total volume being circulated every hour. So, a 5000 gallon pond needs a pump (or pumps) providing no less than 5000 GPH.

Other features or considerations with a koi pond include:

1. No sharp edges. Koi can be very rough, especially when spawning. It is important to avoid sharp rocks, etc within the pond as these can cause serious injury to the fish.
2. Since the koi pond contains few, if any, plants, you should perform partial water changes on a regular basis to remove the nitrates that build up (plants would be using the nitrates if present). A phytofilter can also accomplish this. A phytofilter is an area outside the pond that the water passes through. The area is full of plants and acts as a natural filter.
3. Shade. Without plants shading the water surface, a koi pond in a partially shaded location will help reduce algae and be better for the fish. If this is not possible, consider a pond dye or at least providing shelters within the pond for the fish (shelters will double as protection from predators.) You can also place an arbor, trellis, or other type of shade structure over part of the pond.

By understanding the pond you are installing or already enjoying, your chances of success are far greater.