i just picked up 2 80 gallon tall acrylic tanks. both look pretty new. of course i get both about 1/2 way filled and they leak. no cracks that i can see. can i just clean and seal the tank my self? what is the best thing to reseal an acrylic tank? i wanna do this 1 time and 1 time only. most stuff ive found say aquarium sealant for tanks up to 20 gallons. any help would be aappretiated!