I used an AC coil cleaner that I cant for the life of me remember the name of right now.

Wampole's pontoon cleaner. STAR BRITE 87764 Ultimate Aluminum Cleaner Restorer - Safely Clean Pontoon Boats Jon Boats Canoes 64 oz. It was given to me but you can probably find it at yor local AC partsmaintenance place. Toon-Brite Aluminum Cleaner 12 Gal.

Mill Finished Aluminum Cleaning. Measures for cleaning collecting. The more you dilute the cleaner the less grayish color you will get.

Dispose of contaminated material as waste according to item 13. Our aluminum brightener will clean the oxidation and make the trailer pontoon or any mill aluminum look 100 better. Whichever cleaner you use the general directions are to apply the cleaner scrub it into the aluminum let it sit for several minutes rinse it off and repeat if necessary.

Absorb with liquid-binding material sand diatomite acid binders universal binders sawdust. Allow the toilet bowl cleaner to work into the surface for five to 10 minutes depending on how stubborn or thick the stains are. Rinse the soapy water from the pontoon.

Toon-Brite Pontoon cleaner is designed to remove oxidation lime deposits scum and those hard to remove waterline stains from aluminum boat surfaces. On mill finish aluminum like older pontoons and unpainted flat aluminum panels on aluminum trailers the aluminum turns light gray. Work in small sections to try to avoid streaking the toons.

There is no way on earth to make this. Dip a large automotive sponge in the soapy water. DO NOT GET THE 1 STEP ON YOUR FINGERS.