Ecosystem Ponds Versus Koi Ponds: What's The Difference?

By Oliver U.

If you're interested in adding a pond to your landscape, you've probably come across two very different approaches.

On one side are ecosystem ponds, which are intended to work with nature to deliver healthy water and stunning views. These are built with lots of boulders and gravel, mimicking the geological phenomenon responsible for natural ponds and streams. Ecosystem ponds rely primarily on skimming action, biological filtration, mechanical filtration, and aquatic plants to remove nutrients and neutralize harmful toxins. They are built with longevity and simplicity in mind with very few gizmos

On the other side are traditional koi ponds, which are typically designed around more complex filtration equipment such as bottom drains, rotary drum filters, bead filters, settling tanks, external pumps, and UV systems. When done properly, traditional koi ponds are meticulously designed to ensure coordination between components. The primary focus of a traditional koi pond is to provide healthy, clear water with a dark background, making koi more visible.

Both approaches can be extremely rewarding, but they are designed with different goals in mind.

Let's dive deeper. I'll explain trade offs and specific elements that define each option. At the end I'll reveal the pond type that's preferred by us at NOVA Ponds.

Who knew rock and gravel could be so controversial?

At the heart of the debate is the question ecosystem and koi pond enthusiasts can't agree on; whether to add rock and gravel below the surface of the water.

Besides the significant visual enhancement, rock and gravel serves an important role in establishing an ecosystem. Like a gut biome, the surface is covered in a thin coat of microorganisms called the biofilm. Similar to how a stomach digests food, the beneficial bacteria living in the biofilm converts harmful ammonia and nitrite into a safer compound called nitrate. The stone also provides an essential protective barrier to the liner. I've seen bare rubber lined ponds destroyed by everything from a bear and a human vandal to a tiny mouse. Ecosystem pond supporters insist that rock and gravel over the liner, as opposed to bare rubber, is the right way to build a pond.

On the other hand, koi pond lovers are adamantly opposed to the use of rock and gravel in ponds. They argue that the pleural space between stones traps debris and fish waste. Here's the kicker, they aren't completely wrong! Remember, these are two different systems designed for two different purposes. Traditional koi ponds have bottom drains which act as an intake for the pump and filtration system, pulling debris to the bottom. These are meant to draw debris along the smooth bottom to maintain a clear dark background for koi viewing. Adding rock and gravel to such a system would inhibit the bottom drain from working properly.

Maybe there's a little truth to both sides, and each group is lacking the nuance required to truly understand each other.

Let's compare the filters

The filter in a pond is the most important factor that decides between clear and murky water. Consequently, the type of filter matters.

A bead filter is the most common filter in a traditional koi pond. A bead filter is usually a large above-ground plastic or fiberglass tank with beads that act as biological and mechanical filter media. The filter is controlled by a valve that allows the selection between several modes, including normal filtration and backwash. Bead filters are often accompanied by a blower, which helps break up clumps that form in the filter. Most manufacturers recommend backwashing bead filters every two weeks to ensure they don't become clogged and endure damage. Many koi ponds also include UV clarifiers, which kill single cell organisms like algae. While UV clarifiers can be very effective, the bulbs must be replaced at least once a year to maintain operation. A traditional koi filtration system is relatively high maintenance, although made easier by convenient valves.

A traditional koi pond filter

On the opposite end of the spectrum is the filters for an ecosystem pond. Depending on the pond size, an ecosystem pond is either built with a waterfall filter, like a biofalls, or a wetland filter which can be disguised as an upper triburtary or set beneath a pond. These are both gravity filters, meaning there is no pressurized chamber. The water enters through the bottom, rises through mechanical and biological filter media, and flows out of the top. Because of the simple design, the chance of malfunctions is significantly lowered. This design also reduces the required maintenance; with biofalls needing cleaned 1-2 times per year, and wetland filters only once a year.

A wetland filter on an ecosystem pond

What About Aquatic Plants?

Plants are another important component of an ecosystem pond. Aquatic plants absorb nutrients from the water while providing shade, habitat, and a visual enhancement to the landscape. They contribute to healthy water, and look great at the same time.

Traditional koi ponds can certainly contain plants, but plants are often used more selectively. Many traditional koi pond owners tried to add plants, but were unsuccessful after their koi destroyed them. For a serious koi keeper, maximizing open space and fish visibility may be more important than creating a heavily planted ecosystem.

Our Preference

While we recognize both sides, the NOVA Ponds Construction Team strongly believes in ecosystem ponds for almost all use cases.

As nature lovers, we enjoy building ponds that immerse us and our clients in natural scenery without leaving their yard. The awe-inspiring self regulation found in nature can't be beat by complex human engineering. The added longevity and durability are additional benefits of the simple design.

Because our ecosystem ponds are built with aesthetics in mind, they offer a huge enhancment to a landscape. Ecosystem ponds also use concealed filtration and submersible pumps, meaning there's no ugly equipment in the background. Even without fish, an ecosystem pond serves as a focal point during all seasons of the year.

From a contractor's perspective, we like installing systems that are easy for our clients to understand and operate. An ecosystem pond only needs one electrical device plugged in to run; the pump. The only frequent (~once a week) maintenance activity required in an ecosystem pond is to clear the skimmer basket. We've seen countless pond owners inherit a traditional koi pond when buying a house, and struggle to operate it. New homeowners who aren't familiar with operating valves, priming external pumps, backwashing bead filters, and replacing UV lights tend to neglect koi ponds into disrepair.

A happy koi forages for algae in an ecosystem pond.

The only remaining argument in favor of traditional koi ponds is their ability to optimally house koi. This is incorrect though, as koi aren't intended to live in a rubber hole. Koi are primarily bottom feeders and love foraging through substrate and plants. They'll graze algae off of rocks, and scrape on the stones. Many traditional koi pond owners add one or two small plants, and act surprised when their understimulated koi eviscerate it. A koi living in a traditional koi pond looks lethargic when compared to a happy koi in an ecosystem pond. At NOVA Ponds, our koi are more than display objects, they're living animals that require proper conditions to thrive.

As a Certified Aquascape Contractor, ecosystem-pond construction is a major part of what we do. The goal is to create something that truly belongs there. If you're interested in adding an ecosystem pond to your space, visit our pond construction page!

Like this article? Reach out to us! Send an email at info@novaponds.com or follow our socials.

We're a full service pond contractor serving Northern Virginia, DC, and Maryland.

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