# Is using Silicone I or II in aquariums safe???



## DIY Plant Guy (May 15, 2010)

I would like to create a large lava rock structure for my 55g and for the price Silicone I or II is in a "caulk-tube" for less than $6, but I cant figure out if its safe in an aquarium with plants and fish? Anyone use these silicone products in an aquarium with success?


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## Diana K (Dec 20, 2007)

I have used GE Silicone I and II in aquariums and they are fish safe. Ultimately the seals failed again, but I do not know if I did something wrong, or if it was the silicone. 

Silicone does not stick and stay stuck to rocks very well. Maybe the convolutions of the lava will make it work, but I would try aquarium putty instead of silicone. 

I have also seen super glue used to glue plants to driftwood. However, even the gel type is not really bulky. If your lava rocks did not fit closely together this one would not work.


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## NonSequitur (Mar 25, 2010)

I've used aquamend putty in my reef aquarium with good success (much cheaper than the aquarium specific stuff, but the same product I believe), so that might be a way to look if you need decent holding power.


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## DIY Plant Guy (May 15, 2010)

WIth any success of nice and warm weather I might try the super glue if the sealing strength works well with the texture of the lava rock, but aquarium putty is a nice idea too. If Silicone I and II are safe I may go that route. Thanks for the information and welcome any more advice, I need it!


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## Diana K (Dec 20, 2007)

My understanding is that Silicone II has mildew inhibitors, and is not thought to be good in aquariums. I have repaired several tanks (some more than once), and no longer remember which tank got which material, but have not had mysterious die-offs in these tanks.


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