the tropics where "everything grows" you end up with a brown stain on the hull getting worse from the waterline up. I wipe on the FSR and it's gone. Then I put a fresh coat of wax on the hull and I'm good until the wax goes away and the stain starts to grow again. Then I do it all over again. I get several months worth of a clean hull down there. In San Diego it doesn't seem to be much of an issue.