You should probably speak to
@Eric Sedletzky
as he puts tanks next to other tanks and by the next day or few they turn into more and more tanks
Yes! I put two tanks in the garage next to each other and next day one had twins!
Ask
@Tracy about how steel 72's can breed like rabbits. He has pictures!
Seriously though, lower tank rust, tank boot rust etc. Here's how it goes.
For the bottoms of painted tanks that have been rusting under skin tight tank boots: I sand blast all the rust out and then either epoxy prime or cold galvanize them then send them to hydro. The epoxy primed ones get a topcoat of some color after hydro, the cold galvanized ones are done.
Tank boots: Those Faber ones that are smooth with one little hole in the bottom and fit the tank like a glove, those do not drain. The hole in the bottom is so air can get in to relieve the suction when you slide the boot off. I cut off about half of the hight so it comes off easy. I remove it each time I use the tank and make sure it's clean and salt free and dry before it goes back on. The boot is only so the tank will stand up.
If you have residual rust debris on the inside of a tank boot clean it out well because the grit will foul up your paint job.
You can neutralize the rust with citric acid, or go buy one of those rust eaters like naval jelly or metal prep 79 and it will dissolve the rust, or just scrub it out with a scotch brite pad. Never use rust killer on galvanized tanks themselves because it will eat the zinc away = bad.
Hope this helps.