A friend of mine just told me how to clean scum off a alum boat. I own a alum boat that is painted white and i have tried everything to get the scum line off the boat.A car wash wont begin to get it off its been on there for yrs. He said to put Lysol toilet bowl cleaner on it, let it soak for a few min then power wash it off. I went and bought some went and headed to the car wash.I applied it on to the dry boat like he said, let it soak about 5-10 min then hit it with the power wash. It looks like a new boat!!!:big_smile: I have tried to hand scrub it with all kinds of boat cleaners and never could get the brown scum line off. I guess it has hydrochloic acid ( spelling) which they use to clean alum bulk traliers. It will also clean/shine un-painted alum boats or pottoons. I just applied it to a brush wiped the whole boat down let it soak for about 5-10min then power washed it off.. that simple. Just thought I would pass this along if you want to try it...it works. PS...Wear safety glasses and avoid getting it on you skin.