Empty, dry, reseal.... Over do it more is better lol, test fill... Thats what i had to do when my 220 was leakimg only i didnt know where it was comming from so i litterally resealed the whole tank.... In and outside. And ya if you movw the sand and look at the corners it looks like crap but it dont leak and its covered so idc. But i also had fish in holding tanks so i didnt worry about making it pretty.... Good luck
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