Well the saga continues. They actually recommended that I stick cotton balls in the silencer to correct the issue. Seriously this is expert advice ! Very disappointed with this whole thing. I have ordered a precison needle valve and am going to splice it between the pump and silencer and see if we get better control then a plastic screw. Cotton balls,bah ha ha ha ha what a chump answer ! I am really regrettng buying this online from aqua cave. No support from them at all,it is brick and mortar from now on !