We have a 23' Sea Ray I/O that spends summer in freshwater and winter in the Gulf. Last spring I repainted the hull with Micron Extra bottom paint - over some kind of green bottom paint that was totally shot. It then went into the freshwater. Now it's out of the freshwater and ready to go south again to the salt. There is a brown stain on the hull, just above the waterline/bottom paint. Any suggestions on what to use to get this brown stain? I used to use "Slimey Grimey" when were freshwater only and it was great. Unfortunately, I'm out of it, and it is very expensive here! Any alternatives?