Steel? I use RedKote and have for years. Never had a comeback with it. What I like about it is the inside needs minimal preparation. Clean the big stuff out and rinse w/water,dry well. Apply outdoors 'cause the fumes are rude and toxic. It's original use is agricultural equipment where out of service may mean a season lost. So it is easy to apply and tough. Says it'll seal holes up to 1/16" but I wouldn't push it that far. Kreem sucks. Avoid it like the plague.
Thanks but it is Fiberglass. For steel tanks I use OSPHO but I need to treat this Glass tank against the " Gas" we have today.