Ok, but I've used stress coat before (a year with this skimmer) and two additional years with another skimmer without ever having an issue with bubbles. My water is perfectly clear, I only added stress coat when adding new livestock or water change. I use an ro/di unit for all my water. Every time I do a water change, the skimmer goes crazy, so I have always left off for a couple of days. I will try changing the activated carbon every two weeks and try cranking up in a month. I just hate to have no skimmer running, especially since this skimmer on my 75g was a beast! Thank you