Be careful using Silicone II

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viejafish

Piranha
MFK Member
Jan 31, 2013
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I have used GE Silicone II to glue aquarium objects many times with no issue by following proper curing protocol. Last week I glued another object but in a hurry, I didn't thoroughly cure it before placing into the aquarium. I allowed the glue to air cured for 3 days, but rinsed it only briefly in a bucket of water before placing into the tank. Big mistake! The next day when I fed my fish, none ate and all showed lethargy. I immediately do a 75% WC and removed the glued object, but it is little too late. I lost half the fish from typical ammonia poisoning. All silicone glue releases ammonia during curing. Ammonia poisoning can damage the mucous tissues of the gills, guts and fins. Those that died shortly had no time to develop external symptoms. The survivors showed burnt fins starting out as red streaks a couple days later after the WC remedy. A couple survivors have no tail left, just a stub. I hope the tails will grow back or else the fish will be permanently disfigured and I have to cull them.

It is my mistake by being careless and over confidence in previous successful application. I was assuming that in a cycled tank, a little extra ammonia will be harmless as the BB will take care of it. But it was my miscalculation as I did it in a 30 gal tank and the amount of glue I used was big relative to the tank volume.
 
I have used GE Silicone II to glue aquarium objects many times with no issue by following proper curing protocol. Last week I glued another object but in a hurry, I didn't thoroughly cure it before placing into the aquarium. I allowed the glue to air cured for 3 days, but rinsed it only briefly in a bucket of water before placing into the tank. Big mistake! The next day when I fed my fish, none ate and all showed lethargy. I immediately do a 75% WC and removed the glued object, but it is little too late. I lost half the fish from typical ammonia poisoning. All silicone glue releases ammonia during curing. Ammonia poisoning can damage the mucous tissues of the gills, guts and fins. Those that died shortly had no time to develop external symptoms. The survivors showed burnt fins starting out as red streaks a couple days later after the WC remedy. A couple survivors have no tail left, just a stub. I hope the tails will grow back or else the fish will be permanently disfigured and I have to cull them.

It is my mistake by being careless and over confidence in previous successful application. I was assuming that in a cycled tank, a little extra ammonia will be harmless as the BB will take care of it. But it was my miscalculation as I did it in a 30 gal tank and the amount of glue I used was big relative to the tank volume.
Silicon curing releases ammonia? I've never heard of it... or thoroughly forgot :) Could you please provide a link where you saw it, or would you say it is a common knowledge?

Standard caulking silicon curing releases acetic acid most usually and a LOT of it. But I am looking to learn.

BTW, in our parts, it's GE Silicone I that should be used, not II, because II has anti-mold agents added, which are toxic to fish. Again, correct me if I am wrong.
 
I'm not familiar with the chemistry associated with silicone adhesives, but I question the ammonia thing as well. It would have to be a crap ton of ammonia to overwhelm the nitrifying bacteria in your tank. A whole bunch of silicone at once.
 
BTW, in our parts, it's GE Silicone I that should be used, not II, because II has anti-mold agents added, which are toxic to fish. Again, correct me if I am wrong.
You are correct. More than likely that is what happened here, the anti mildew agents that are used in GE II will kill your animals. GE I is what you need to use. I have made many aquariums using GE I and have had no problems.
 
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It said right in the label of Silicone II that during curing, it will release ammonia and methanol, and I can smell ammonia. There are acetic acid based silicone too but it is a different type. The label also says Mold Free, but no mention of anti mold agent in the ingredients. Just about every caulk is labeled mold free but useless as mold grows on organic dirt accumulated on the surface of the caulk.

Silicone II releases a lot of ammonia during curing and whether it will harm the fish depends on how thoroughly you let it cure, how much you use, and how large the volume of water to dilute it. I have used Silicone II safely many times with thorough curing. They are back in my tank now after soaking it up overnight and rinse in several buckets of water. I didn't buy the caulk gun type silicone, but the type that come in small toothpaste tube so I can store and resuse for a long time. GE only sells Silicone II in tube.
 
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Interesting. Thanks. Sounds like I got my homework to do :)

Would you please post a picture of the label so that's it's legible, front and back?
 
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Sorry about your fish. :(

Also, if it makes you feel better, if your tailless fish heal up and there is no bad secondary infections or other damage I wouldn't worry too much about culling them. I have a mbuna with no tail and he swims around fine thinking he still has one haha. Apparently he was like that for years according to the previous owner. Musta been bitten off at one point.
 
According to this product list, GE offers at least 19 different brands of GE Silicone II.

http://www.caulkyourhome.com/pdfs/GESiliconeProductGuideSheet2013.pdf

Some of these do indeed describe methanol and ammonia as odors that occur during use. However as they are all different, it's important that the OP identify which one he bought. It's always been my recollection that people nearly always advise using GE Silicone I, not II. True or just anecdote?
 
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^ i was also under the assumption that everyone used GE I and not II as well...
 
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