From what I have read, mostly here at PB...

1.) Diffusers at the bottom maximize the aerobic decaying process.

2.) Diffusers at the bottom maximize a consistent temperature from top to bottom while potentially reducing the surface temps to the greatest extent (given that one does not over-aerate and super heat the pond).

3.) Diffusers off the bottom minimize turbidity issues by not stirring up clay and/or silt.

4.) Diffusers off the bottom are believed to leave somewhat of a thermocline for heat relief for the fish.

It's my deduction that those in cooler climates are less likely to need that lower thermocline for heat relief and bottom placement makes a lot of sense unless you have clay that will stir up and suspend while the warm climate pondmeisters should try and maintain that lower thermocline and sacrifice the benefits of a full aerobic atmosphere all the way to the bottom. Those in between the warm and cool climates need to experiment a bit more and may even have to move some diffusers around at different season if they wish to maximize the benefits of aeration.

I live in Missouri and my experiment, thus far, is working out fine.

I have a 10 foot deep 1/4 acre pond with 3 diffusers. One is placed towards the middle at 7 foot deep while the other two are near the edge at 4 and 5 foot deep. All the diffusers are on stands that put them 20 inches off the bottom. I believe my pond is turning over entirely as the temp at 7 foot deep is only one degree warmer than at 10 foot deep. I do not have that lower thermocline that I was shooting for, but I don't think I need it as the lower temps are typically in the low to mid 70's. It would appear that I have found a sweet spot, quite by accident, that does not increase turbidity, but turns the pond over entirely.

My 2 cents.





Fish on!,
Noel