I havent tried this but it sound GREAT!
"Cleaned 2 tanks using the following method, and was shocked at the results. Plus it was a lot of fun. Everyone that saw it eventually did their tanks as well. Cost 50 cents for the salt, and a buck for the rebar I used.
Mix 1/2 canister (about 13 oz) of common table salt with 3 gallons of water.
Block the petcock and sending unit holes, then fill the tank right up to the filler neck so that all inside metal is covered with the salt water. Use fresh water to fill as needed. You will add extra salt later.
Make an electrode out of something steel (I used some 18" x 3/8" rebar I had laying around). This will go into tank, and must NOT touch anything metal in or on the tank. Use a plastic funnel at filler neck to prevent touching, and use a wad of tape at bottom of rod to prevent touching. Make sure tape goes up far enough so that tank hump does not touch rod.
Use a "manual" battery charger of at least 10 amps.
Connect negative cable clamp to rod.
Connect positive clamp to tank. I used the tank mounting bolt.
(flow is positive to negative, so rust will leave positive charged tank and go to negative charged rod).
Turn on the charger and adjust your charging rate to get as close to 9 or 10 amps as possible. Add more salt to increase charge. I had to use almost all of the canister to get near 9 or 10 amps draw on each tank.
You will see bubbles forming and the water will turn brown.
First tank was spotless in about an hour!
Jaws did drop! We expected something to happen, but nothing this good.
Second tanks was rough, and it took about 3 hours cooking before it too was spotless. This second tank was for a ninja, and the dealer told him tank was junk and could not be cleaned or used. WRONG! 6 months later it is still like new.
You can reuse the solution. Turn off charger, remove rod, empty tank, and look at results. Pour solution back in and restart process if needed. It's cheap enough to use a fresh batch each time.
Watch the rod. The second tank ate away the rod at one spot about 80% through. Change if needed.
I found this by searching various methods. Google and see similar methods. Most describe sodawash instead of salt, but it takes longer. Salt works!
No sealing of either tank was needed. Rust was removed, not metal.
Where there was rust, there is now a darkened scar.
When done, rinse dry and coat tank right away. Tank will start to rust again very fast. I used tranny fluid to coat tank.
WARNING: I think this creates a type of Chlorine gas, so don't stand above the tank, looking into it while cooking and breath the fumes. Be smart and use normal precautions. (well ventilated area outdoors, etc)."
