I've resealed several tanks and the largest was 800 USG. If there's a key element to keep in mind it's that if you're sensitive to chemical exposure the fumes from a reseal can be a booger. Worse yet is that several sites will recommend that you clean the old sealant out as best you can and then clear the residue out w/ acetone. I'm 100% certain that stuff eats brain cells. I highly recommend ventilation and lots of it.