Met people that simply swear by :
Sno
Bol
It's a spray toilet bowl cleaner. Said they tried everything...then "bottom Dave" recommened this. Said it was unreal...spray on and watch it dissapear...no scrubbing!
Thought I'd pass it along
Frank- all that is is diluted Oxalic Acid. Sold in hardware stores as WOOD Bleach.
A pint can of crystals costs way less than the toilet bowl cleaner, and you can mix as you need it. Makes GALLONS.
I carry a container aboard Tehani always.
DON'T get it on your inflatable- it will bleach that too
I used to clean boats as a summer job. I second, we used the $1 toilet bowl cleaner containing oxalic acid from the dollar store. It also removes rust stains from fiberglass, fish hooks, bait wells etc.