My Pond “Turned Over” …What Now?

Pond turnovers, though a completely natural occurrence, can be quite alarming for landowners with stocked recreational ponds and lakes. Picture this: you walk out to your pond on a beautiful day and see nothing but floating fish! Yikes! Luckily, a better understanding of why ponds endure turn overs can help pond and lake owners manage the effects.


“Pond turnover” is a term used to describe the mixing process of different layers of pond water. Typically, in hot summer months, ponds and lakes tend to go through a temperature stratification which separates the water into layers. As time goes on and weather changes these layers can mix, causing a depletion in the dissolved oxygen of your body of water. As the cooler water from the bottom rises and the warmer surface water sinks (and vice versa!) it can throw your fish for a loop as they suddenly do not have enough oxygen in the water column to survive. A depletion of dissolved oxygen results in many, if not all, of the fish dying. This mass-die off is traditionally called a “fish kill”.


Depletion of dissolved oxygen can happen in other ways, too. A rapid die-off of vegetation (which can happen with herbicide use) causes the aquatic plants to cease the photosynthesis process, resulting in a major decline of dissolved oxygen in the water. But do not fret! There are some key things that pond owners can do to lessen the effects of a pond turnover.


Aeration systems are a huge help in general for any pond, but especially for smaller ponds harboring a high volume of fish. An aerator can work in two ways—it can disturb surface water in a fountain-like manner (like an agitator), which allows semi-deep surface water to be exposed to oxygen before landing back in the pond, or air bubblers can be set on the bottom of a pond to blow air evenly throughout the water column. One thing to mind with the latter method is the fact that bottom aeration systems have the potential to kick up nasty ammonia from the muck and silt that lies on the bottom of ponds. Ammonia is a major issue for fish, and the less of it present the better! Essentially, aeration systems keep water cooler in the hot summer months and discourage stratification, all while actively exposing water to more oxygen in some form.


In addition to aeration systems, being mindful of chemical usage is crucial. Too much chemical too fast can crash oxygen in a pond due to the rapid decline in oxygen-producing vegetation. It is recommended to follow directions closely and monitor treated ponds for any signs of fish kills.


Aeration systems are readily available at Henneke Fish Hatchery, as well as proper aquatic vegetation chemicals. Our trained professionals walk you through step-  by-step to ensure your pond or lake has a decreased chance of falling victim to pond turnovers. Come out and see us today!

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