# Is my silicone safe?



## bmlbytes (Aug 1, 2009)

I made a protein skimmer for my aquarium, but have yet to put it to use. When I sealed it, I used 100% silicone. I thought that was supposed to be safe for fish. Just recently I learned that some tubes of silicone have an anti mildew chemical in them that may harm fish, even if they are labeled as 100% silicone. After doing some research, I find that both GE-I and GE-II are safe for aquariums as long as they don't have the anti-mildew. Here lies the problem. I did not buy GE brand sealant, I bought ACE Hardware brand sealant. I have no idea weather or not it has the anti-mildew. It says it is architechtural grade sealant. Does anyone know what ingredient would be the anti-mildew?

The ingredients listed are:
Silica (68855-54-9), Ethyl Triacetoxysilane as Acetic Acid (64-19-7), Silicone Fluid (mixture), Dibutyltin Dilurate (77-58-7)

Anyone know if any of these chemicals are harmful to fish?

Also, in my research I have read a lot of people say don't use the anti-mildew, but not one report of it actually harming their fish. Has anyone heard of it actually harming fish?


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## lohachata (Jan 27, 2006)

look on the label for the manufacturer and contact them about the anti mildew chemical..or contact ace hardware HQ and ask them....i have a friend that built a 50 gallon breeder not realizing the silicone had anti mildew agent in it..everything he put in that tank would die.and i had warned him about the dangers and to read the label..and he still bought the stuff..it's a good thing he is my friend or i wouldda slapped him in the head for bein so dumb..
from the looks of the formulation of what you used;i don't think you will have any problems...they all seem to be relative to the sealant itself and not any other agents..

silica,,base of the compound..
acetic acid compound is what gives it that vinegar small.
silicone fluid is what it is.
and the dibutyltin is another part of the compound..key word there is "butyl" = rubber...kinda sorta..
but not anti mildew agents in there...


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## emc7 (Jul 23, 2005)

Its a stabilizer rather than a mildewcide, but has some toxicity.


> The toxicity (EC50/24-48 hours) of mono- and dibutyltin compounds with the water flea, Daphnia magna, is at concentrations of 1 to 10 mg/L [24, 25, 26], and dibutyltin (EC50/48 hours) with oyster larvae at concentrations of 0.1 to 0.2 mg/L


 In other words in 48 hours at a concentration between 1 and 10 mg/Liter, half the daphnia die. So in the range of ppm. Now the compound is prob. only a few % of the silicone, will have to work free, and does break down into less toxic mono- and inorganic tin. But from this data, I can't say its entirely safe. dibutylin has also been observed to have reproductive effects in rats. So its possible it wouldn't kill your fish, just mess up the breeding.

Neither GE silicone I or II has any organometallic additives if this site is right. http://whatsinproducts.com/information.php?brandNo=07-011-005


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## bmlbytes (Aug 1, 2009)

I looked up each ingredient by the number next to it. Apparently the acetic acid is used as a fungicide in many products. Although I don't think it would hurt fish. We eat acetic acid in almost all of our food. 

Dibutyltin Dilurate is used as a catalyst to make the silicone dry faster. 

Would it be safe to run water through the protein skimmer for a while to make the harmful stuff absorb into the water before using it in the aquarium? I would think that at some point the harmful stuff would have to stop leaching into the water, otherwise the silicone wouldn't be water proof.


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## emc7 (Jul 23, 2005)

I don't suppose you have access to a gas chromatograph to measure levels. I think the levels should be below toxic amounts, but no promises. Acetic acid is just vinegar, I heard of people adding it to tanks to lower pH. The only issue with that is pH. A newly sealed tank will often drop the pH of its first tank of water. Taking apart and replacing the silicone would be a real pain. Could you put some sort of sealer (maybe another layer of another silicone) over, just to be safe.


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## lohachata (Jan 27, 2006)

go to your local fish store and buy a tube of "Silicone Aquarium Sealer"...most likely manufactured by Dow Corning or General Electric.....
that way you won't have to worry about wether or not it is toxic to your fish..


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## Obsidian (May 20, 2007)

They already used it Loha. 

Personally I would do what Loha has suggested, however what you need to do is make that you have very thoroughly cleaned the old stuff off. 

OR do his earlier advice and just call the manufacturer and ask if it has a mildew protectant in it. Really shouldn't take long at all.


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## bmlbytes (Aug 1, 2009)

The problem is, I don't know what brand actually makes the ACE brand stuff. I know ACE doesn't make it. It is like the Aqua-tech brand fish supplies. They are the Wal-Mart brand, but they are made by the same company who makes Tetra and Marineland equipment.

Oh and to reseal it, I would have to cut it open, which is something I can do, but don't want to. 

My tank is pretty small, and so water changes are not that difficult. I know a protein skimmer will help keep it stable, but in this case maybe not. I may just try to find a small protein skimmer online.


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