GE Silicone I or II

for the red tube, from HomeDepot website, it says it's "stable"

 

...which means nothing regarding possible toxicity.

Why is it rated for bathrooms? It it's because it has anything in it that has been added as an anti-mildewing agent, you don't want it in your tank.

 

are you talking about the GE Silicone 2+ blue (not for bathroom or kitchen) or red tube (for bathroom and kitchen)?

I had a tube of the red one left over from recaulking the bottom of my shower, and used some to glue river rocks to some artificial plants to weigh them down.

I'm talking about GE 100% Silicone 1

 

Hi,
I don't think we get the GE brand here in Aus, but here's what I know about silicone here in Aus.

Most, if not all, Kitchen/Bathroom silicones have mould inhibitors, and as jjohnwm mentioned, it's not nice stuff (I can't remember the additive either). They have this inhibitor as they're often used in very humid environments, which encourages mould growth, and is an absolute pain (impossible) to try and clean from silicone.

Then there is the All Purpose, 100% sealant type silicone. which I think the GE is, designed to seal, but not 'stick'. It's often used to put on cracked tiles and to stop leaks. But some of them haven't been tested under pressure.

Then in Aus, we have 100% glass silicone. This stuff is meant to keep glass stuck together, under pressure, mainly for high rise buildings etc, but is also fine for aquariums.

So for baffles, I'd have no problem with the AP silicone, as the pressure is equal on both sides, but to build an aquarium, I can't be bothered finding the right one, I'd just buy 'Aquarium Silicone'; might cost more, but at least I'd know it's the right one.