LB - your temperature measurements to me indicate the shallow end would marginally benefit from some minor or low strength circulation since there is only a 5F difference between surface and 5 ft. At 4 ft the water is mixing pretty good or normally from wind and convection - IMO. Notice at the deep end at 5 ft deep there is clear stratification where the temperature difference is 9F and at 6ft the difference is 14F, indicating a pretty strong thermal stratification. No mixing occurs below 5.5-6ft deep in your pond unless there would be a significant weather event. This indicates the deep part of the pond would benefit most from bottom aeration. Depending on the size and location of the diffusers, this mixing and associated currents could easily expand into the water 3-4 ft deep to keep it more evenly mixed.
Water below 6ft deep at this point in time (May 31), likely has no DO or very little dissolved oxygen (1-3ppm). As the season progresses more oxygen will be lost in all the layer below 5.5-6ft. I guess it has not Do since your water clarity is only 12".
Your bottom temperature of 66F at 8ft deep indicates that your pond stopped mixing top to bottom this spring when the water 'reached' 66F; then DO loss began.
Last edited by Bill Cody; 05/31/16 08:01 PM.
