I did some preliminary research [youtube] on zinc plating, using electrolysis, you need both a zinc anode and cathode for that particular process. I was toying with the possibility of either zinc or tin plating the inside of the tank once it was rust free. BUT this electrolysis process isn't for plating it's for the reduction part of a RED-OX Reduction/oxidation reaction on the rust in the tank. The rust [oxidation] is reduced [removing the oxygen] with the steel wool rusting in the solution, which also absorbs the freed oxygen as it rusts and provides the electrons that the iron of the tank needs to turn back into it's rust free state. The liberated oxygen also wants electrons because it likes electrons basically. The electric current through the mildly conductive solution is what makes all of that happen. Zinc isn't particularly reactive, you could try it, but I suspect it would just sit there unaffected. Steel wool works fast, wish I'd thought of it first time around as it would have saved days of dumping and refilling the solution and having to constantly scrape the rust off my electrode
Steel wool!!! Awesome idea! I'm going to use electrolysis to de-rust tank that's been sitting for 15-yrs!