QUOTE (Dizzle21 @ Nov 9 2009, 09:11 PM)

I guess ill help a fellow contestant out..
what i used was silicon worked really good! just filled it with water tonite "FW" and it was all water tight. you can use aquarium silicon or use GE-II silicone from hardware store. Its been proven safe when cured.
Check out my thread "After i start it cuz im makin it right now..hah"
GOODLUCK!!
+1 to GE Silicone (as long as it doesn't have the mold/mildew resistant). Never used it for a reef tank, but used on several FW tanks will no ill effects. Just make sure it fully cures before you add water (I'd leave it a couple days).
Good luck!