Yea I have my reservations as well, but I figured for the price its worth a shot. I've read a lot and it seems people say most if not all waterproof epoxies cure to be non toxic and inert. I will definitely be testing in a tank without the fish in it first and making sure water quality is not degraded before putting it in my display tank. I will be giving it at least a week or two to cure before doing so and if there is any funny smell at all after that I will not be putting it in my tank.