I have read that GE I has no mold protectors so it is the best to use for aquarium use, and is cheaper as well. But i have read about this new GE Silicone II K/B that is 100% silicone and is supposed to seal in about 1 hour approximately. I am assuming it is safe because it is 100% silicone, i need a second opinion before I buy and seal with this. Thank you everyone