[need louvers ?]

if the vinegar doesn't do the trick, try CLR from the hardware or grocery store. in either case, after the tank is as clean as you want it to be, take a bit of time to soak some water and baking soda in it to neutralize the acid and prevent further rusting... Trust me on this one.

 

[need louvers ?]

Absolutely! Don't spill it on the tank! I have always topes around the neck and used a plastic drop cloth taped to that to keep any spills off of the paint. baking soda and water for sure after either or you can sit and watch new rust form.

 

[need louvers ?]

Worst and or best it can do it delaminate the old sealer inside, which is what you want anyway. Just think the CLR would do it quicker. I have actually spilled that product on lacquer paint and quickly wiped it up with no I'll effects... Just don't do if you can help it. For sealer, Caswell has been working great for me!