We can find fish to eat the scum off the inside of a fish tank but not off of boats.
Seems like a mad scientist could score with only minimal mad scienceing.
Well the one thing I know is I haven’t been able to find any environmentally friendly stuff (the kind we’re supposed to use) that works. I hit it with vinegar last weekend and it didn’t even touch it. I’ll put my Soft Scrub in a different bottle and use it.