[A930Rocket]

Title says it all.

Every once in a while, someone leaves a nail or screw in a tub or shower pan that’s holding water. In no time, the screw/nail rusts and leaves a spot.

I’ve tried CLR, baking soda and lemon juice, Bar Keepers Friend, Iron Out, baking soda with all the chemicals combined as a paste, etc. and scrubbing like a mad man. It never works, even letting it sit overnight.

I had a tub repair guy that had a chemical he used in a partially filled tub of water. It always worked but he wouldn’t tell me what it is. Then he wouldn’t be needed. He costs me $125 for each tub.

Anyone have a tried and true method of rust removal on fiberglass?