I picked up a bottle of the Instant Rust Out at Menards for use on the PWC. I don't have a lift for the PWC and it floats in the water all season, it's been in since May and pulled it this past weekend, it had the typical brown scum on it. Before it had a chance to dry I sprayed it down with the Rust Out and a little soap and water with a wash mit made the bottom of the hull look new again with little hassle.
Thanks for the tip!
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05' Chaparral 220 SSI
350 Mag / B3
Seadoo GTS