Sorry for you loss. It can be devastating. Like the summer 05 storms in MO that cooked and killed my tank while the power was off for 3 days while I was out of town.
However, I do not think you are doing the community a service with the title of the thread.
Our hobby is predicated on building knowledge, and that is based on facts. Not opinions or hastily based conclusions.
The fact is that many others including I have used GE silicone II for many many years without problems!!!
The fact is also that some people have had horrible things happen to their tanks shortly after using GE silicone II.
The conclusion that based on the second fact alone GE silicone II is always toxic is not a fair and valid one.
Everything is toxic under certain circumstances:
Kids drown in 1 inch of water.
The NaCl (salt) in my lab has a toxic warning on it. 50 ppm salt will kill most fish, 35 ppm is blissful.
Sucrose (sugar) ground finely is very flammable.
Silicone II is a neutral cure silicone (it releases ammonia and methanol). Both of these are very toxic to animals. After it has cured pure silicone is viewed non-toxic (safe for drinking water applications). Except PERHAPS the mold inhibiting versions (kitchen and bath) that have some anti-mold agents in the silicone. I haven't seen any solid data these actually cause problems in reef tanks, but it certainly is possible.
Silicone I leaches acetic acid while curing. Acetic acid is much less toxic to fish (we even add it to calcium hydroxide (ball pickling lime) to increase solubility of the calcium.
But both silicones are essential inert after curing.
So why do people use II?
II sticks better to plastics than I, and I sticks better to glass then II
I literally just used GE silicone II clear on saturday evening to reseal a bulkhead. I dropped the level of the tank below the bulkhead, pulled the bulkhead out , cleaned it, resealed, it waited 24 hrs, refilled. Corals were fine before. Corals are fine after.
My larger 140 g tank is completely sealed with Black GE silicone II. I did by let the silicone cure for weeks before I put in fish and corals (siliconed before leaving for vacation). But many other times I've used GE II sealed tanks after 24 hrs or even less (just o.n.) . The fish are fine. The corals are fine.
SO, please don't just blame GE silicone II without reflecting on the situation.
You used GE silicone II. Your fish died. These are facts.
How and/or If GE silicone II lead to fish dying is not necessarily clear.
If you did not wait until the silicone cured (24 hrs, not just the 3 hr setting time), then it could be the Silicone II releasing ammonia and methanol. However, in that case, it is your fault for not following directions. It could be some independent event (pulling fish out and placing them in a holding facility, etc is all very stressful for fish).
I can understand if this experience makes you restrict you use of silicone to the "aquarium safe" labels. But it is just not as clear as Silicone II is toxic and kills fish.
In any case, I hope in the future that you will start a thread with facts rather than conclusions and let the community help you derive at the cause of the mishap (or disaster in this case).
Mike
