I've read up about Evaporust. Apparently its a environmentally safe way to get rid of rust. You just soak whatever you want and then you can just dump what's left and it won't kill anything. I want to eventually try using this for my tank, but I thought I'd first experiment on my rusted triple tree.
It ate through the rust, and also took off some of the paint (which I don't mind because I want to repaint anyways). It said that It wouldn't damage powder coating...I think it only took off paint because it was chipped due to the rusting anyways. On to the tank!