What silicon should I use?

Dalescarpentry · Apr 6, 2014

It seems that I read on here somewhere that GE silicone can be used for aquariums. I was at Home Depot on Friday and read the back on about every brand of silicone they have and could not find one that was aquarium safe for under the water line. Please help. Thanks Dale

Reefing Madness · Apr 6, 2014

Dow corning 999A
Dow Corning 735
RTV 100 Series Silicone or SCS1200
GE I Silicone, but I'd use this if I was only doing a small project with glass. Same with using GE II. Either of these can be used, but you must let this stuff cure properly, the uncured silicone is the stuff that will kill a tank.

hybridazn · Apr 6, 2014

Reefing Madness said:
Dow corning 999A
Dow Corning 735
RTV 100 Series Silicone or SCS1200
GE I Silicone, but I'd use this if I was only doing a small project with glass. Same with using GE II. Either of these can be used, but you must let this stuff cure properly, the uncured silicone is the stuff that will kill a tank.

I agree with all of the above except the ge II. That type has the mildew inhibitors that will always leach into your system, do not use. GE I doesn't have the inhibitor and is safe to use after curing.

stunreefer · Apr 6, 2014

GE I turns yellow in saltwater over time, FWIW. I stick with 'aquarium specific silicone' nowadays.

hybridazn · Apr 6, 2014

stunreefer said:
GE I turns yellow in saltwater over time, FWIW. I stick with 'aquarium specific silicone' nowadays.

Interesting, any idea on how long it takes before it starts to yellow? I've uses this on numerous sumps and reseals. I've had my sump running for 3 years and haven't noticed any yellowing of the silicone.

Dalescarpentry · Apr 6, 2014

Thanks guy's

lucky7 · Apr 7, 2014

All glass aquariums silicone is what I always use

mfinn · Apr 7, 2014

You can't go wrong with either of these.

Amazon.com: All Glass Aquarium AAG65010 Silicone Sealant, 10.3-Ounce: Pet Supplies

MOMENTIVE Silicone,Clear,10.1 Oz - Sealants - 4UH12|RTV108 12C - Grainger Industrial Supply

JSaquatics · Apr 8, 2014

I always used Aqueon silicone never had any problems

_Alex_ · Apr 9, 2014

+1 to the momentive rtv mentioned above. It's what most aquarium manufacturers use.

Newwaterville · Apr 10, 2014

I have used GE 1 on several sump chambers. I have never had an issue. Matter of fact, I just used it 5 days ago. Larger sump for my frag tank. I got it running 2 days ago. :0)

stunreefer · Apr 15, 2014

hybridazn said:
Interesting, any idea on how long it takes before it starts to yellow? I've uses this on numerous sumps and reseals. I've had my sump running for 3 years and haven't noticed any yellowing of the silicone.

Mine started within about two months after my most recent use (circa summer 2012). I don't expect you to see if if it's been running three years

I've used this on baffles for my personal sumps for years and hadn't had any issues until the last sump I tried it with. Wrote it off as it didn't cause any livestock issues. Put another sump together for a friend and his turned yellow in about the same time (also no issues with livestock, just yellow silicone). I have to think that they added something else into the silicone fairly recently that causes the yellowing.

VicD81 · Apr 21, 2014

How long do we let GE1 cure before its "safe"? Im going on day 7 and I want to leak check it for a week then it will prob be dry for another week for aquascaping. would that be fine?

eg8r210 · Apr 21, 2014

VicD81 said:
How long do we let GE1 cure before its "safe"? Im going on day 7 and I want to leak check it for a week then it will prob be dry for another week for aquascaping. would that be fine?

I think the amount of time to wait also has to do with how thick. There are people that tell you to wait 30 days and I think that is ridiculous. If you put it on real thick it is going to take a little extra time but for me 24-48 hours is long enough. Also, I would probably wait a little longer if my system was smaller. I read online that the GE I cures and releases ammonia. Well my system is about 300 gallons and the little bit of ammonia that "might" have been released into the tank was never measurable.