The toilet bowl cleaner cleaned it beautiful, but then it stated turning brown or rust colored and I want to know something to clean it with, that will clean it and the brown won't come back.
The bowl cleaner temporarily removed the tubs resurfacing rust; an increasingly browning film stain. But probably too well; also dissolving away some of the tub's enamel. You'll want to find a balance between removing just enough brown film stain routinely; while not dissolving too much enamel. I suggest a lesser strength acidic cleaner, and rinse it off sooner, and very thoroughly. Unlike your tub, toilet bowls don't have an under laying iron frame, so rust can't resurface... Good luck, take it easy, and think about a replacement tub sometime. Long term, I that's a better deal, than "painting it". I'd like to buy stainless tubs, sinks, and toilets.