The effects of spring and especially fall turnover can be devastating to your pond. Turnover problems may not happen every year, but if turnover does occur, it could ruin a large investment in your pond. The best ways to prevent turnover or at least minimize its effects is to keep the water mixed and add supplemental aeration.
When wind and wave action fails to sufficiently mix the pond water and eliminate or push the thermocline further down in the water column, it is advised to physically mix the water in another way. There are two types of equipment that work best for mixing water; Water Circulators, and Bottom Diffusers.
Water Circulators – This type of equipment works by creating directional flow that can also be pointed downward. They can be angled in several positions and can successfully mix deeper ponds and create directional flow, while providing some oxygen. They can also be mounted in variable water depths and used to prevent ice in winter. Kasco offers horizontal circulators known as Water Circulators/Mixers.
Diffused Aeration – This type of equipment uses a pump on the shore to push air through a weighted tube to an air diffuser on the bottom of the pond. The air then bubbles through the diffuser and rise to the surface, carrying vast amounts of water with them. The rising bubbles carrying the water help to mix the water and prevent layering. These work best in deep ponds where a good circulation can be set up. In shallower ponds, they do not operate as efficiently.
While diffused aeration is great at addressing large and/or deep ponds, caution should be taken when installing after a thermocline has been established. A slow-start procedure is best to avoid creating an artificial pond turnover by forcing the cold, dense water to the surface through the lifting action of the bubbles.
Another way to limit the effects of turnover is to add supplemental aeration. Using an aeration device, you can help mix the water as discussed above, plus add vital oxygen to the pond system. If an aerator is in place before turnover occurs, even if the pond turns over, the added oxygen will help to prevent a massive fish die off and create a buffer for major problems associated with turnover.
Surface aerators are a great option for adding oxygen to the water and will also help to push the thermocline down to about 5-10′ depending on size. The added oxygen will be great for your pond all season and the mixing will help limit the amount of water moved during turnover. If turnover still occurs, the aerator will help save your fish and your pond. Typically, it is recommended to have about 1hp of aerator per acre of water to properly aerate the pond.
By adding equipment to mix the water column and add vital oxygen to the pond, you can create a better pond ecosystem throughout the year and eliminate or limit the negative effects of spring and fall turnover, which can be devastating to your pond.