Thats what I thought, but I bought a tube of silicone II from HD and it said not for use in aquariums, but it doesnt say if its because its toxic or not strong enough. My guess is the latter, but im just making sure!
Some silicones have toxic chemicals in them. I believe it is cyanide but I can't remember for sure. I would only use Silicone that says it is safe for aqauriums myself.