Ok so i go to petsmart with my friend who needed to get feederfish. and the guy was like hey do you want a 20 gallon? i was like suree... so i picked it up later and it had dirt in it he said there was lizards in there before sooo i just filled it up outside and its still sitting there full of water im tryin to see if it holds water..the stuff thats usaully silicone is like a white tape but on there pretty good so im wondering should i start setting it up? is it gonna hold water!?! can it be used for fish with that silicone stuff and also there are a few rust spots at the bottom anyone know how i can get that off? thanks