Proper Koi Ponds vs. Aquascape Design Ponds (Water Gardens)
The purpose of this article is not to bash any company or product, but rather to help educate hobbyists planning to build a backyard water feature with the ultimate long-term goal of providing a healthy ecosystem for koi and goldfish. Over the years we have helped many pond owners redesign and upgrade their failing Aquascape designed and built ponds by converting them into proper Koi ponds.
Based on our experience there are 6 critical design features every proper koi pond must have. While Aquascape contractors commonly love to use the terms “balance” and “natural” during their sales pitches, the reality is it is not possible to ensure optimal koi health without these key features. You can avoid many common headaches and regrets later on by taking these points into consideration before starting your own pond build. 6 Critical Features for a Proper Koi Pond:
1. Bottom drain (located at deepest point in pond, multiple bottom drains for large ponds)
2. No rocks or gravel covering pond floor (this is very bad for Koi!)
3. Minimum pond depth of 36” (deeper is always better)
4. Proper koi pond filtration (skimmer filters and waterfall filters alone are not sufficient)
5. Air pump (waterfall alone is not sufficient for aeration)
6. UV clarifier (Ionizers and algaecides greatly risk Koi health and barley straw doesn’t work)Additional Recommended Features for a Proper Koi Pond:
1. Pond skimmer (for removing floating debris from your pond surface)
2. Pond jets (to provide optimal water circulation while pushing floating debris towards skimmer)Common Pond Design Flaw #1: No bottom drain
First and foremost, a proper Koi pond should always have a bottom drain. We often say the best pond vacuum you can ever own is a pond bottom drain. The reason we say this is because adding a functional bottom drain to a properly designed koi pond often totally negates any reason to ever buy a pond vacuum. In essence, a pond bottom drain is vacuuming your pond floor all the time.
A bottom drain serves several key purposes within a koi pond. All fish waste and other debris will ultimately settle towards the pond floor where it will be removed by the bottom drain and then sent to your filter for removal. Ideally, a pond bottom drain should be installed at the deepest point in your pond and located as far away from the primary water return as possible to help maximize water circulation.
If you decide not to install a bottom drain in your pond then you will come to regret it. In fact, in nearly two decades we have yet to come across a single pond owner who built their pond without a bottom drain who didn’t later come to wish they could go back in time and decide to add one. Unfortunately, by the time many pond owners come to realize their mistake it is usually too late and a complete pond rebuild is often required in order to fix the issues caused by this fatal design flaw.
One common rationale for hobbyists who choose not to install a bottom drain is their understandable fear about cutting holes in their pond liner. Well, fear not because today there are several quality retrofit bottom drains available on the market which should help to alleviate these concerns. So if you don’t feel comfortable cutting holes in your pond liner then please be sure to add a retrofit pond bottom drain
. We promise you will never come to regret making this decision. Common Pond Design Flaw #2: Gravel and Rocks Covering Pond Floor
The water in Aquascape design ponds is extremely unsafe for Koi and other pond fish, not to mention unsafe for humans and your other pets. Why do we say this? Because using gravel and rocks to cover your pond liner creates a prime breeding ground for all kinds of pond nasties. Muck, fish waste, and deadly fish pathogens all thrive within the rocks and gravel. This reality ultimately results in poor water quality, sick koi, and if left unchecked for long – dead koi.
A proper koi pond should not contain any rocks or gravel, period. You can still line the edges of the pond surface with rocks to help create a natural appearance; however, no rocks or gravel should be placed within the water itself. The pond floor should be totally smooth and slightly sloped towards the bottom drain, which should be located at the deepest point of the pond.
While an Aquascape design pond may look good to the untrained eye in the beginning, after the first year or so the water within these glorified water gardens commonly becomes extremely green as water quality continues to deteriorate. Due to this fatal design flaw, the maintenance workload for the pond owner often becomes more than they bargained for.
Because they are unable to effectively clean their ponds on their own due to all the muck hiding under the rocks and gravel, many of these unhappy pond owners resolve themselves to paying a monthly fee to a “certified” contractor to effectively clean their ponds for them. Again, if their pond was not full of rocks and gravel and if it had a bottom drain then these expenses and dirty work could be avoided. Common Pond Design Flaw #3: Pond Too Shallow for Koi
A proper koi pond should have a minimum depth of 36” while deeper is always better. Whenever possible, we highly recommend a minimum pond depth of at least 48”. Another common flaw of most water gardens / Aquascape design ponds is they are extremely shallow. A shallow pond experiences wide temperature fluctuations which can be dangerous for koi and other pond fish.
Unlike other fish, koi growth is not limited by the size of their environment. Most Aquascape design ponds are less than 24” deep. Extremely hardy, it is not uncommon for koi fish to still grow to well over 24” in length while residing within these shallow puddles marketed as koi ponds. Shallow ponds also contain less dissolved oxygen content, meaning aeration can be a major problem during summer.
Simply put, shallow ponds get too hot in the summer and they get too cold during the winter to provide a suitable living environment for koi. While koi are classified as cold water fish, they do not do well in extreme temperatures. Just like you, koi can experience sun burn during the summer. In addition to the dangers of temperature fluctuations, sustained temperatures below 40 degrees or above 90 degrees Fahrenheit -- common in shallow ponds -- can also be deadly to koi.
Stable water conditions are required in order to provide a healthy ecosystem for Koi and this is simply not possible in a shallow pond. If your pond is less than 36” deep then we would highly recommend not adding koi. A few feeder goldfish may do just fine, but larger koi cannot thrive within a shallow Aquascape design pond no matter what your certified contractor may try to tell you during their sales pitch. Pond Design Flaw #4: Inadequate pond filtration for koi
Proper biological filtration is required for any water feature in which koi and other fish are kept. The biological filter media used within any pond filter is designed to provide surface area where nitrifying bacteria can grow. These nitrifying bacteria can also be found on virtually any surface area in your pond, including on your pond liner and on your pond waterfall.
While the word “lie” may be too strong for some, I will use the word “misleading” without any hesitation when describing the filtration commonly installed on most Aquascape design ponds we have helped customers upgrade over the years. In the vast majority of cases, biological filtration within these ponds is provided solely by whatever biological media is located within the pond skimmer and within the pond waterfall weir.
The media commonly used by many Aquascape pond installers is lava rock. Unfortunately, lava rock is not effective at all as a biological filter media. It is commonly used because it is cheap, no other reason. And more often than not, this lava rock will ultimately need to be replaced within the first year as it quickly clogs and becomes a breeding ground for deadly anaerobic bacteria.
Recognizing the failings counting on a skimmer and waterfall filter alone, over the years additional pressurized water garden filters have commonly been installed as optional upgrades. Sadly, in our experience these small pressurized canister filters often provide only minimal improvement when it comes to water quality. These filters serve only as a temporary band aid, meanwhile the main problem – the fatal flaws of the pond design itself remain unresolved.
In our experience it is virtually impossible to sustain a healthy ecosystem for large koi without a properly sized koi pond filtration
setup. Pressurized bead filters specifically designed for koi ponds are commonly recommended by experienced pond builders for anyone with a highly stocked koi pond. Other popular alternatives when it comes to pond filtration include sequential pond filters and moving bed filters, both of which have their own pros and cons.
Our main point when addressing pond filtration is that you cannot provide a consistently healthy ecosystem for koi if your only filtration includes a waterfall filter and/or a skimmer filter. And any certified contractor who tries to convince you that you can achieve some kind of balance using these filters alone is inexperienced, woefully misinformed, or simply lying to try to make a sell. Adequate filtration is absolutely paramount when caring for koi fish. Pond Design Flaw #5: Inadequate Pond Aeration for Koi
We have assisted many pond owners who were absolutely convinced by their Aquascape pond installer that their waterfall alone would be able to provide enough aeration for their entire pond. This is simply not true, and when it comes to larger koi this kind of mistake can often prove deadly in the warm summer heat when dissolved oxygen levels in your pond is at its lowest.
If you plan to keep koi in your pond then you need an air pump, period. There are many quality pond aeration pumps on the market today which are both economically priced and effective so there really is no reason for any pond owner not to have one. There is a difference between aerators designed for outdoor ponds and air pumps designed for use in indoor aquariums. Most aquarium air pumps are vastly undersized for use in koi ponds.
As the need for pond aeration has become increasingly more difficult to deny, this option is now commonly offered as an optional upgrade by many water garden installers. Sadly, a real experienced koi pond builder would never allow a customer to build a proper koi pond without already including the cost of a pond air pump as part of the original pond build. Without sufficient pond aeration, you cannot safely care for koi and resulting fish deaths are a virtual guarantee. Pond Design Flaw #6: Lack of UV clarifier to eliminate algae blooms
A properly sized pond UV clarifier
is the only 100% effective solution for green water caused by seasonal algae blooms. Many algaecides and chemicals commonly marketed to help clear pond water are not safe for koi and other pond fish. When sizing it a UV clarifier for your koi pond, we recommend 20 watts for every 1,000 gallons of water in you pond. For example, a 40 watt UV clarifier should be more than sufficient to achieve consistently clear water within a 2,000 gallon pond.