As long as its 100% silicone its (assuming) safe. I have never had problems from using 100% CLEAR silicone. I know ACE Hardware, along with Lowes and such sell it. Just make sure you allow proper drying time. Also, Pet Supplies Plus on Coldwater is probably the cheapest place to buy a tank when I was pricing them. But, I have noticed petwarehouse has come down alot on their prices though.