I used Penguin Bio Wheels exclusively for the first few years I got into keeping fish. Sometimes they do that when the impeller housing isn't seated right. Usually happens when you break them down to clean them and restart them up again. I pull the impeller housing up a little bit and then firmly push it down again so it seats right. This could be what's wrong.
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Clarence 
55g sumpless mixed reef(soon to be 120g)
DSB(2 to 6 inches)aprox. 80 lbs,LR aprox. 60 t0 80 lbs.,Coralife 220 Protein Skimmer,CPR HOB Refugium with Fiji Mud
Member of TRS Member of SDMAS
RIP Sarracino Ciro 12/16/04 - 4/3/08
