SLUF681
Well-Known Member
There are many questions about whether or not certain silicones are "aquarium safe" or not. I wrote this explanation some time back and thought I'd throw it on our forum for current and future members to easily find. Most people know that GE silicone I is "safe" and that GE silicone II is "not safe". Unfortunately, most people only know that because someone screamed it from the top of a mountain long enough, and loud enough for everyone to believe it. It is simply not true.
GE silicone I is an acid cure, meaning that acetic acid (vinegar) is the curing agent. That is why you smell the vinegar smell. GE silicone II is ammonia cure, meaning that ammonia is the curing agent. Silicone I needs 24 to 48 hours to cure. Silicone II needs 7 days or more. Just make sure you don't buy the Kitchen and Bath in either one, just to be on the safe side. I've used BOTH GE I and II.
I used the black GE silicone II to reseal one of my tanks that I sold. The guy has freshwater discus fish. No harm whatsoever. The ONLY reason to use "Aquarium" silicone is if you completely disassemble the glass panels. "Aquarium" silicone is silicone ADHESIVE and actually has a tensile strength rating. Most silicones available at Lowes, Home Depot, etc are silicone SEALANTS. If you are simply resealing a tank, just use any NON kitchen and bath silicone. If you want to use black, go to home depot and get a tube of GE silicone II. If you want to do clear, simply use GE silicone I.*Once again, GE silicone II is simply an ammonia cure. No evil fairy dust or nuclear waste in it.
I did a great deal of research into what was in different silicones before I re-sealed my first tank or built my first sump. Silicone is inherently mold "resistant". I was never even able to find a "Mold Resistant or Inhibitor" in the MSDS for GE I window/door/attic, GE II window/door/attic, or GE II kitchen/bath. A call to GE netted no answer to the question of what the mold inhibitor ingredient was either.
For the record, I was advised by GE that they DO NOT recommend the use of ANY of their silicone products to be used in aquariums. I called DAP and got the same answer, with the exception of their "Aquarium Sealant". Upon asking what made the "Aquarium Sealant" safe, I got an answer of "I don't know".
I suspect after reading all the horror stories on the forums the problem isn't the silicone, but the impatient aquarist that doesn't allow enough time to cure. All the stories are the same. "I re-sealed a tank I just bought with GE II the day before yesterday. It's a 55 gallon freshwater. Yesterday, I put my gravel in it, filled it up with tap water, put a new HOB filter on it, and put 10 tetras, 3 Jack Dempseys, 5 Oscars, 15 Gouramis, and a 15" Pleco. Today, everything is dead except 1 tetra. What do you think the problem is?" Inevitably someone replies "I bet it was the silicone. You didn't pay enough for it. You have to use the stuff that says aquarium on it."
GE silicone I is an acid cure, meaning that acetic acid (vinegar) is the curing agent. That is why you smell the vinegar smell. GE silicone II is ammonia cure, meaning that ammonia is the curing agent. Silicone I needs 24 to 48 hours to cure. Silicone II needs 7 days or more. Just make sure you don't buy the Kitchen and Bath in either one, just to be on the safe side. I've used BOTH GE I and II.
I used the black GE silicone II to reseal one of my tanks that I sold. The guy has freshwater discus fish. No harm whatsoever. The ONLY reason to use "Aquarium" silicone is if you completely disassemble the glass panels. "Aquarium" silicone is silicone ADHESIVE and actually has a tensile strength rating. Most silicones available at Lowes, Home Depot, etc are silicone SEALANTS. If you are simply resealing a tank, just use any NON kitchen and bath silicone. If you want to use black, go to home depot and get a tube of GE silicone II. If you want to do clear, simply use GE silicone I.*Once again, GE silicone II is simply an ammonia cure. No evil fairy dust or nuclear waste in it.
I did a great deal of research into what was in different silicones before I re-sealed my first tank or built my first sump. Silicone is inherently mold "resistant". I was never even able to find a "Mold Resistant or Inhibitor" in the MSDS for GE I window/door/attic, GE II window/door/attic, or GE II kitchen/bath. A call to GE netted no answer to the question of what the mold inhibitor ingredient was either.
For the record, I was advised by GE that they DO NOT recommend the use of ANY of their silicone products to be used in aquariums. I called DAP and got the same answer, with the exception of their "Aquarium Sealant". Upon asking what made the "Aquarium Sealant" safe, I got an answer of "I don't know".
I suspect after reading all the horror stories on the forums the problem isn't the silicone, but the impatient aquarist that doesn't allow enough time to cure. All the stories are the same. "I re-sealed a tank I just bought with GE II the day before yesterday. It's a 55 gallon freshwater. Yesterday, I put my gravel in it, filled it up with tap water, put a new HOB filter on it, and put 10 tetras, 3 Jack Dempseys, 5 Oscars, 15 Gouramis, and a 15" Pleco. Today, everything is dead except 1 tetra. What do you think the problem is?" Inevitably someone replies "I bet it was the silicone. You didn't pay enough for it. You have to use the stuff that says aquarium on it."
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