Pond Boss Forums AERATION Systems questions Compressor/Diffuser Pressure Question

Theo and Steve have good points. Both will register a little bit difference in pressure. More so with Theo's Hypothosis.

I would dare to say with a 3 psi change, you may have dropped your diffuser down to a deeper depth. If you are achieving a larger and "nice rolling boil" this would increase the amount of bottom debris that is being entrained into the water column. Your 9" diffusers have dug themselves a hole and the increased pressure is the result.