I can't seem to figure out what is wrong with my filter. I am only 2 weeks new at this whole pool life. There are zero air bubbles in canister but yet my return has little bubbles coming out of it when the filter is running. I am assuming there is air somewhere but if its not in the canister, where else do I check? I have back washed with no luck in resolving the issue. I also noticed more oils on the top of the pool water lately but not sure if the issue is related. That can be from use. Anyone know what I should check or do to stop the bubbles? Are the bubbles even ok and that is normal. I have not noticed this the first week of use.