If you've used it already, then you probably won't have a problem. I thought you were buying new sand.
I see. That's good news then. I tested the seals and there were no leaks, so it's nice to have thin inner seals so they won't be so apparent. I've seen new tanks in stores that have gobs of silicon in the corners.I have that same exact kind of tank, with the thin seals and glass center bar. At first I was worried that the seals are too thin, but the tank has been full for te past 2 months, so don't worry about it.