What Circulation Can Do for You

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-Written by International Sales Manager, Joe Holz

If aeration is one of the best forms of overall pond management and the best way to balance a pond ecosystem, circulation is a close second. Circulation, just like the blood in your veins, is critical to a healthy, vibrant pond ecosystem. Without circulation, natural biological processes become imbalanced and do not function properly, leaving undesirable consequences in the pond.

Luckily, you can kill two birds with one stone using an aeration device as most of these products also involve a varying degree of circulation and water movement. Therefore, you not only get the benefit of the improved DO and all the benefits that go along with that, but you also see improvement with the most common stagnant water issues like stratification, turnover, winterkill, floating plants and debris, and mosquitoes.

Beautiful Backyard Pond


The layering of water by temperature and density can cause major problems within a pond like limiting fish habitat, slowing down decomposition processes that lead to harmful gas production, and dangerous chemical properties within the pond. Using and aeration or circulation device can prevent and in some cases eliminate this stratification completely.

As with many things in life, it is easier to prevent a stratification problem before it starts. Therefore it is recommended to install and start an aeration or circulation system in the spring before the layering has occurred. Once it has occurred, you can still address it, but you need to take caution to not inadvertently create too rapid of a mixing that would lead to a turnover in the pond.

Adding these devices to the pond will at the very least extend the oxygenated surface area to a much larger volume than naturally seen, and in many cases eliminate the layering completely, leaving your entire pond available for fish use and eliminating the risk of a turnover related fish kill.


This is the process of a layered or stratified pond mixing when density barriers are lost, typically in the fall. This can be catastrophic for fish if oxygen levels drop too low. Adding a circulation or aeration device can eliminate this risk completely by removing the stratification of the pond. It will also add valuable oxygen to buffer against any such turnover or mixing.


In the North, lots of ice and snow can spell disaster for your fish. As ice and snow build up on the pond, it blocks out sunlight which plants need to grow. Without plants, no oxygen is being produced. If you have a large density of fish and large numbers of big, adult fish, the oxygen stored in the water could be depleted before spring thaw can help introduce more oxygen. In this case, your fish could begin to die due to lack of oxygen, and since larger, adult fish use more oxygen, they may be the ones to die first.

Winter circulation or De-Icing, can help prevent this winter die off by creating openings through the ice and snow to allow oxygen to absorb into the water. Cold water can hold vast amounts of oxygen, so all you need to do is expose the water to the air and oxygen will literally jump into the water. No splashing is needed. According to studies done by the WI DNR, only 1-2% of the surface area of the pond needs to be ice free to prevent a winterkill situation.

By circulating the warmer bottom water to the surface, you can successfully keep an open area in the pond. The temperature gradient does not need to be large to prevent ice formation. In some cases, you can even melt existing ice if a circulation or de-icer is installed after the ice has formed. This can take the worry out of wintering your fish successfully and set your fish population up for rapid growth once the water warms in the spring.

Floating Plants & Debris

Circulation can also help limit debris and floating plant growth in your pond. Creating a moving water environment in your pond will turn your pond into more of a river environment. Floating debris can be better managed by pushing it into areas where it can be removed easily. This is especially important for ponds in more urban areas where trash can find its way in or around docks, marinas or boats. In some cases such as marinas or bays, strategically placed circulators can prevent floating debris from entering the area altogether. Circulators have been successfully used to direct floating debris to areas where it is either not seen or where it can be more easily removed, saving time and money.

Moving water also deters some floating plant species from growing. Most floating species of plants prefer still, stagnant water. If that water is moving, growth is limited or prevented altogether. The faster the water is moving at the surface, the less likelihood there is of having major algae, duckweed, or other floating plant problems. The water just does not sit still long enough to allow for excessive growth of these plants.


Often the arch nemesis of any pond owner, mosquitoes can be a major detractant from having a pond. Part of the mosquito life cycle depends on still, stagnant water areas where the mosquito larvae can “hang” onto the surface tension of the water. By introducing circulation and movement to the water, you can disrupt the surface tension, causing the mosquito larvae to sink and drown. Since mosquitos can reproduce in tiny puddles and very small amounts of water, simply circulating the water in your pond may not be enough to get rid of all your mosquitoes. However, you can at least attempt to manage some by making sure your pond is always moving.

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