The Works bathroom cleaner.

Muratic Acid.

This stuff works great.

Liquid Sno-Bol toilet cleaner. Inexpensive, found in any supermarket and comes with a handy sprayer.

Make sure you rinse really well with the On/Off!

The "Work" cleaner did it. He had it clean by the time I got there.

SLX is what i have used for along time, its a gel, put it on your brush and rub it on the stain best stuff i ever used.SLX can be found at any boating store

Snow Bowl Toilet bowl cleaner -- You need rubber gloves and goggles for your eyes:Old clothes!

5 boats 20 years most often slipped

I've never had any discoloration/stain on gel that on/off wouldn't take out, period.

same hydrocloric acid ingredient as the bowl cleaners that's why some report there positive experience with it.

by far more % by volume hcl in on/off

I use BIO-KLEEN Oxidation remover. It takes off the yellow Keystone lake staines. I think they will be at the poker run this weekend as a sponser