I just resealed a 75-gallon and a 58-gallon for use....I completely removed all of the silicon on the inside of the tank...carefully...using a single-edged razor blade. I emphasize carefully because if you aren't careful and deliberate you can cut yourself. Once all the silicon is removed from every surface inside the tank, I placed a strip of masking-tape a little less than a half-inch from the corners and one at a time put a bead of silicon into the corner and with my finger spread it so that it went from the corners to the edge of the masking-tape. Remove the masking tape after just two minutes or so. This gives neat edges to the silicon so it doesn't look messy. I did it over the course of a few days to do all the corners. Remember, silicon needs to fully cure over at least 48-hours before you put water in. Once all the siliconing is done...fill the tank a few inches and wait a little while to check for leaks. This way, you'll be sure that there are no leaks at the bottom....Then after that keep going up a few inches or so and check so that if there is a leak, and most likely there will not be....you'd be able to have some idea where it is that way.
