I got a free 55 gallon that needed resealed as well. AFter the first time of resealing, it lasted about 2 weeks and then the seal broke and I had LOTS of water on the floor. This time, I thought I had done a much better job of sealing it. Waited 2 weeks and decided okay, I had done it right this time, so I began putting in some decor and got the some other items ready to get it in....thankfully, the black sand that I ordered hadn't arrived yet, because after a MONTH of having resealed the second time, the seal broke again. AAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHH, I JUST WANT TO SCREAM!
I am going to give it one more shot, but I sure will sell it as a reptile tank if it doesn't hold after this! If anyone has any sure proof ways to seal, I sure would like to hear them. Good luck on your sealing job. I didn't want to discourage you, just want you to be cautious and realize that sometimes, you may think you have done it right and then.....