B
Bob Rutland
Most hull cleaner's main ingredent is Oxalic Acid and sell for about $28 per gal. I found a product at Home Depot called Rustaid(used to remove rust stains from houses) that also contains Oxalic Acid for about $8 per gal. It works very well on those ugly rust stains your boat gets at the waterline. Be careful not to get it on Aluminum or painted surfaces. It will also streak bottom paint (just like most hull cleaners).