I'm going to look at a used 45 gal hexagon aquarium w/stand. Price is right, I am exercising some caution based upon the tank's history. It was manufactured 2005-06 time frame, and was utilized as a salt water-reef system. The owner said he "re-sealed" the aquarium not too long ago, and assured me that it was "water-tight" (I'll ask him to demonstrate this). I asked if that involved just replacing the silicone caulking?, he responded as if he disassembled the fish tank and re-glued it. I don't understand why you would completely tear apart a fish tank. I can understand cutting away old silicone caulk, then re-caulk with new sealant. My wife wants to bring our 2 comets indoors from a small water tub/garden. They're only about
2 inches long. I read that you should have 20 gallons per goldfish. I don't know why you shouldn't use gravel, but use sandblasting sand. Sorry for the lengthy questions & post. Thank you for your help/info in advance.