I have recently been fighting a losing battle with ich in my 65 gallon tank with several convicts. When i first added the infected fish to the tank i was using the same gravel vacuum as my 90 gallon tank before i knew it was infected. (i know i should have quarantined them but im new to the hobby) its been three weeks with no sign of ich in the 90 gallon but is there any steps i should take before there is an outbreak in case it got contaminated. I have africans as big as 9 inches in there i would hate to loose.