So... we found out the hard way when our waste tank has reached capacity... it seems our Full tank light comes on and then it has reached the absolute max.... no room for anymore. We were trying to be good new boat owners and were using plenty of water in our techma toilets. Anyway we woke up to a slight overflow dribble out of the waste port that has stained our fiberglass deck. Any advice as to what to use to remove this? Our boat has been recently detailed so the fiberglass has been waxed but it stained anyway.