Aquarium safe silicone?

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Sinister-Kisses

Sinister-Kisses

Aimara
MFK Member
Jan 19, 2022
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BC, Canada
I'm on the hunt for some black silicone that is safe to use on one of my tanks. I'm scouring the local home improvement store websites trying to find something they have in store I can go out and grab today rather than ordering online and waiting for delivery. However, amongst the billions of freaking silicones out there it seems finding a black one is pretty hard to do, and then finding one that might be aquarium safe makes it near impossible.

I found this one - obviously it doesn't NEED to be high temp for a tank, BUT it caught my eye because it says it's 100% RTV silicone and doesn't say anything about mold or mildew inhibitors which I know to avoid. I did a quick Google search because I wasn't sure what RTV silicone was, and it seems like RTV silicone is okay for aquariums in theory. So, is this something I could use in a tank?

PS - I'm not actually resealing an aquarium. I'm looking more for like siliconing decor items together that will be submerged, etc.

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I live in a REALLLLLLY small town on the west coast of Canada. What you people think is common place, is non existent in a store here for me lol. Petsmart carries a small tube of aquarium silicone but it's clear, and I have clear already at home. Was hoping for black.
 
I used this with great success when making rock decorations
Aqueon Aquarium Silicone Sealant Black 3 Ounces

They have black and clear in three packs as well.
 
I know there are lots of options if I want to order online. I'm trying to find a tube I can pick up in store today. What I showed and asked about is the only local pick up option I can see so I'm wondering about that specific product.
 
I have used a product called Geocel 4500 Roof, designed and sold as a roofing repair sealant. I looked all over for it (after doing a lot of online research) and eventually ordered it online...and then a few months later I saw it on the shelf in my tiny little local Home Hardware!

Awesome stuff, excellent adhesion to glass, EPDM liner material and also epoxy-finished plywood. I seem to recall that it was a bit more expensive than the cheapest silicones, but far cheaper than the impossible-to-find Gold Seal and 5200 sealants. Super sticky, a little messier to work with, but for the purposes you describe it would be terrific. I'm not sure if I would build an all-glass tank with it, but as a sealant or non-structural adhesive it's perfect. It's been in service for over a year now, sealing together the individual panels of EPDM liner material with which I lined a plywood build and also sealing the EPDM to the glass front.

Try your local hardware store; ya never know! :)

Edited to add: If all you are doing is assembling decor, consider using plain old 2-part epoxy glue. Dries clear, much less visible and obtrusive than "'clear" silicone. A little goes a long way, and it's non-toxic when cured.
 
Lol the one I showed IS digging deep at my local hardware store. Thanks.
 
Momentive RTV 103 and dow-corning 795 are two of the strongest black silicone adhesives i know of that adhere to a lot of different materials well. Both are tried and true in aquaria related usage. RTV103 is acetoxy cure and DC795 is neutral cure. They both cure to more of a dark grey than black.
 
Thanks. I'm just gonna go a different route I think.
 
It looks to me like you found one that should work fine right out of the gate. If it's 100% silicone it has no additives and if it's suitable for food contact it also can't have much by way of nasties in it. I'd give it a whirl myself.

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