I wasn't totally happy with my arrangement using a CO2 bubble counter as a silencer to reduce noise of spitting and bubbling from it and thought the only reason it's noisy is the fact air can't escape fast enough from the housing. My second attempt is much simpler in that I decided to drill 5 1/4" holes in the top of the housing and position it 1/2" above the waters surface. Now my HOG2 is all but silent as the air escapes much easier and stops the spitting of water from it and by having it 1/2" out of the water I don't get either the spitting sound or the sound of bubbles. The 1/2" of all but dry area is insignificant and in fact is much less then when I had it totally submerged as an airpocket would form inside due to the fact the air previuosly could not escape fact enough. here is a pic taken from above shoing the holes I have drilled and with my HOG 2 in place on my sump.