Rust Removal - Fuel tank

[u09521]

some of the experienced guys suggest pool acid but not sure how to use it and neutralize it again afterwards maybe one of the experienced guys can comment further

I used 10l pool acid and rest water. Let it stand overnight and all rust is gone. I neutralized with a box of bicarb. The problem is just it rusts immediately again, so you have to do something pronto. I sprayed some WD40 type stuff around the inside, but it still needs more. Maybe swish some diesel around in there.
and BTW if you leave the fuel cap on with the acid inside, the inside parts will vaporize...