I purchased a used 06 Century 2200 Walkaround. I have run twice to the open ocean off Charleston for bottom fishing. While anchored or drifting I have noticed a bubbling noise from the inner hull/bilge. It literally sounds like bacon cooking and is loud enough to hear on the open ocean! It is not isolated to one area its everywhere. When I returned to the launch I check all the compartments again and it was gone I have had an ant problem from parking lot storage but I have fumigated and powder treated for them and have not seen ANY in a month. Any ideas/input would be greatly appreciated