I am is southwest Indiana. I have 6 pumps and 8 diffusers going in a 25.4 acre lake. On 8-13-06 temperature was 85 top 5Ft. 85, 10 FT. 85, 15 FT. 85 Oxygen was top 4.5, 5Ft. 4, 10 Ft. 3 and 15 Ft. was 2.5 Ph was 8.2 Hope this helps