Pond Boss Forums AERATION Should I aerate? Windmill is pumping, but can't open holes in ice!

One has to be cautious when you start bottom diffused aeration after oxygen depleted water develops on the bottom. This applies to winter and summer aeration. The thickness of the depleted oxygen layer on the bottom can vary depending on several things, but it depends mostly on the eutrophic nature of your pond and water clarity. More nutrient rich and more turbid the water usually means a faster depletion of DO that will occur. The faster it occurs the thicker the bad water layer becomes.

When you begin bottom aeration after depleated oxygen conditions occur on or near the pond bottom, it can cause decreased oxygen and toxic water problems throughout the pond as the currents spread out and mix the water. It all depends. Rank smelling water is a sign of toxic water that is caused primarily by hydrogen sulfide. Hydrogen sulfide is very soluable in water and in low concentrations it is toxic to fish. Normally, depleted oxygen in ponds begins near the bottom and proceeds upward toward the surface where dissolved oxygen (DO) is usually the highest. If you move a large amount or enough of the DO deficient and toxic gas water to the surface this can degrade the top water enough to kill your fish. Some species and sizes of fish are more tolerant to low DO than other fish. Low DO and toxic gases are a double threat or stressor to your fish. One may not have killed them, but together, all or some may not be able to tolerate both conditions.

The best thing to do for winter aeration is to set or suspend the diffuser in shallow water. When the diffuser operates it oxygenates the surface layer first. Then the currents gradually spread out away from the diffuser enlarging the aerated zone both shallow and gradually towards the depths. As the low DO develops on the bottom and becomes intolerable to fish they will instinctively move upward towards generally better water quality.

The local newspaper outdoors writer called me today about low oxygen problems in ponds at close to the end of our current harsh cold snowy winter. When the article appears Friday, I will provide a link to it.