Reef Safe Caulking

[tim the toolman]

Definitely not. Most bathroom silicones will have a mold and mildew resistance and therefore leech chemicals into the water for quite a long time. Many on here swear by GE II silicone available in black and clear. I personally have used the home hardware clear silicone which is quite fairly priced and actually says safe for aquariums right on the front in large letters. I'm sure others on here will chime in with alternatives as well. Good luck