Sarc, You have a very good pump as the Gast 0523 is the "flagship compressor" of waters less than 16 ft.Your diffusers are a question as far as turnover but are perhaps an EDI model with 1 mm I slits and receiving approx 2 cfm each and your pressue guage should always read in the 5-7 lb range. A guess at a turnover rate would be just that. Also always tough to know how much credit to give to wind action and normal mixing from temp swings.Lets just say I believe there is more room to error on the side of running them too little as compared to too often. Look into a YSI DO meter sometime and I think you would enjoy the information you would get from it on a year round basis. Let me know if you have the 3/4 inch blue BRADY check valves in your lines and I may have a tip on how to improve your air supply considerably.Ted