with the model # we can look up the cfm at your placed depth. 1.5 is probably open air volume. Rocking pistons usually deliver nearly that much up to several psi. FYI...each 2.5 ft of water=approx. 1 psi. If you're at 12 ft...about 5 psi.
Before I had my pond reworked, I placed the diffuser inside a 5 gal. bucket to keep from stirring up the sediment.

Last edited by burgermeister; 06/17/10 09:08 AM.