I've used ge type 1 windows and doors with no issues.

http://i287.photobucket.com/albums/l...8/silicone.jpg

Here ya go.

This is the one that Ive been using and have never had any issues.

silicone
 

that's not safe for aquariums-it has a mold inhibitor in it

The GE Silicone I - Window ver has no mold inhibitor in it. I have used it for my reef and I have had no issues.
But then again, its up to you. Everyone has their own oppinions and you can get the silicone made for aquarium use =p

Just be safe and use what is supposed to be used. It's really that simple. Why take any chances if you plan on having 1000's of dollars worth of stuff in your tank that could potentially die.

GE SCS1200 Construction silicone, or any other brand purchased at local aquarium stores. Don't take chances with your fishies!

I've always used this as well, except last time, everything in the tank died. Someone posted in another thread that after contacting GE, it turns out that they changed the formula for this product. So while you might get lucky and buy older stock off the shelf, for me, I'll just use the GE 1200 from now on.

Yeah. I just checked homedepot's website and they seem to have a new one. If you are going to use the GE silicone I, use the old one. You can tell by lookin at the label design.