So long as the water does not contain any debris larger than the diffuser "holes" or air passages it should be a non-issue. The water will just be blown out once the system is turned on. I suspect systems that get turned off allow water to seep back into the line as the air pressure backs off, but the diffuser would act like a filter and not allow anything into the line that could clog the interior of the diffuser.

Disclaimer: I don't know pond aerators, just my 1/2 cent.


Fish on!,
Noel