Bottom diffusers are used to move water to the surface (and back to the bottom), not to add O2 to the water. Think of bottom diffusers as water pumps. Surface aerators are O2 injectors.
The waterfall is a great O2 injector. It is one of mother natures bests O2 injectors!!
Flyer,
Not sure about your statement here? Bottom diffusers do move water to the surface from the bottom of the pond as you said, but its my understanding (unless I am wrong) which I could be, as that water hits the surface of your pond it is then re oxygenated. Hence the reason for a bottom diffuser. To push deep water that has no D.O. back up to the surface to get more 02. and then cycle back through again and again.
RC
