Pond Boss Forums AERATION Systems questions aeration depth??

He is right about there being no thermocline. He is wrong about the fish having a guaranteed summer haven of cooler water if there is a thermocline.

In a small body of water such as yours and mine, the thermocline that develops in summer is almost always wasted water space that is devoid of oxygen and can't support fish. Fish can not survive in the water below the thermocline for very long, if at all. Toxic gasses such as Hydrogen Sulfide from decaying matter quickly build to lethal levels in this non-aerated, cooler, "summer" water also. Aeration overcomes both of the issues of toxic gasses and low dissolved oxygen, and makes the entire water coulumn usable for fish year round. I have yet to see a pond that did not benefit considerably from adding bottom diffused aeration.

Summer aeration should have the diffusers placed at the deepest point and the second diffuser where it will move the most water. In the winter, move the diffusers to a more shallow depth to prevent super-cooling your water.

If there is a danger of the water becoming too warm during the summer, you can run the aeration at night only when temps fall below 70-75*.

Bottom line is the guy you got your fish from SHOULD know the species you listed are not too upset with the slightly warmer water. In fact, without aeration, having a thermocline, and warm water, the perch would possibly die in the summer.

Personally, if my fish supplier had told me what your's did, I might look for another fish source. Growing small fish such as those from a fish farm is not particularly hard to do....growing them big and maintaining high quality water is however, exceedingly hard to do with any consistancy!