GE Silicone II for tank sealing

[Khemul]

I just resealed a tank with Silicone II, still debating on ripping it up and starting over with a different type (it worked fine filled with water but no fish/substrate yet).

Here is what the research I've done has come up with....
At one point GE Silicone II advertised "mildew/mold resistant" which is bad for the tank. This later changed to "with Bioseal" which basically means the same thing since the Bioseal is what was being added to make it mildew/mold resistant. Now the bottles make no mention of mildew or mold. The only difference (according to the bottle) seems to be strength. Silicone II is supposedly 80% the strength of Silicone I. Not sure how significant that difference really is in this situation.

A lot of people still claim the anti-mold/mildew stuff is in there, just not listed. I personally find this odd since if you look at the kitchen/bath silicone they make a big point of mentioning the anti-mold/mildew propeties of the product. Seems rather silly for them to include the same stuff in the window/door silicone and decide there is no need to even mention it at all (even in small print).

One thing we can find out quickly from comparison is that 100% silicone does not mean that nothing is added to the mix. Just look at the kitchen/bath stuff, which is listed as 100% silicone. They arn't saying that 100% of the ingredients are silicone.


The main problem with the anti-mold/mildew stuff seems to be that it is a strong bacteria killer, meaning the tank may never cycle. Granted with the amount of silicone compared to the volume of water and the amount of leeching over time. Well basically research will show you a huge debate on whether it hurts anything or not. Unfortunately it is difficult to get a straight answer on this. You will have 'experts' on both sides claiming anything from dead/mutant fish to no effect whatsoever. If you contact GE they will probably tell you not to use any of their products, but typically the stuff sold as 'aquarium sealant' is produced by GE just not sold under their name. It isn't really a lie or false advertisement, just that they refuse to warranty their product for aquarium use.

 

[andyjh]

Fine reseach and analysis. I think I'm going to stop shy of ripping it out and starting over. Think I'm gonna roll the dice on this and throw a few fish in and see what happens.

 

[Dagamoth]

I do not know what the actual real life tests have proven regarding the use of II but i do hear that it has a mildacide in it. To think about mildacides/biocides/antimicrobials...the active ingredient of Head and Shoulders is Zinc Pyritheon(sp?) and guess what? It doesnt kill us, it just prevents dandruf(sp?) and cleans our hair.

So how bad can it be? how much can leach out? Does it kill plants? Can we cycle a tank that uses II instead of I?

BTW: mildacide.

Quick question, do you breath your head and shoulders and drink it 24/7? Fish don't really have the option to rinse and dry off after being doused with H&S.

Personally I would just go ahead and reseal the tank right now before adding any fish. It might be alright to go ahead and add some fish but if they start dying off you'll need to reseal it anyway but you will have killed some fish and wasted money on fish. Also I have no idea about your filter media, would the moldicide leach into that and slowly release later?

I have a tank that I kept having fish die off in that i had bought on craigslist. There was some black silicone on the seals. No idea what kind it was but i went ahead after fish kept dying and resealed it. Haven't had any die in it since.

 

[phil47952]

Guess I'd better not use this stuff for my reef tank..... I had always thought if it doesn't anything about mold it was safe...


Hello all, I've been around awhile just never posted

Phil

 

[WeedCali]

I also had another thought, what if you just went over the II with some I?

 

[Khemul]

Guess I'd better not use this stuff for my reef tank..... I had always thought if it doesn't anything about mold it was safe...


Hello all, I've been around awhile just never posted

Phil

Good idea. A FW setup can risk it. A FOWLR setup maybe can but still wouldn't be a great idea since reef setup is sometimes a future transition of FOWLR. Too much expense in a reef setup though to take unnecessary risks. Much better to pay the small extra expense and a few more days to be 100% sure.

 

[wesleydnunder]

Find some Dow Corning 100% silicone and be done with it. Never have to worry about what's in it.

Mark

 

[andyjh]

Another thought might be that just because the cured product contains a mold/mildew inhibitor doesn't necessarily mean that its leaching out of the cured product at toxic levels. I think I'm going to attempt setting this tank up as if this little incident never reared it's ugly head. I'll report back later on how the tank's doing.

 

[dbosman]

The issue of biocides in Silicone sealant comes up periodically in every fish fourm. It usually runs just like this one. Some say yes, some say no, but hardly anyone has experience. When they do, they usually don't remember the specific product name.
There are hundreds of Silicone sealants, caulks, adhesives, and so on.
Some of them will leach and others don't. Some are engineered to do things others aren't. Based on our shower, the biocide in the bathroom sealer doesn't work very well. ;-)

An engineer for Dow Corning, chimed in once and said that the reason silicone sealers hold glass together is that they fill micro pores in new glass and keep the glass from pulling away. His advice was to not to reseal smaller tanks - purchase new ones. He also suggested flipping the glass - if you were going to rebuild a tank - so the glass to glass surfaces were as pristine as possible as it was impossible to get all the old silicone off or out of the glass. Your mileage may vary.

One common feature of silicone sealers is silicone won't stick to silicone. Unless one adds a large enough bead to cover the old silicone and adhere to glass, it will just peal off later.

If one intends on keeping expensive fish or plants, I suggest scrapping all the sealant away and resealing the tank. Don't cut into the glass to glass seams.
If it's a community tank, based on my years of reading these threads, I'd not worry - if the tank cycles and fish are still alive and healthy after a couple of months.

 

[andyjh]

The issue of biocides in Silicone sealant comes up periodically in every fish fourm. things others aren't. Based on our shower, the biocide in the bathroom sealer doesn't work very well. ;-)
.

Truer words were never spoken. If the stuff were that powerful, killing everything around it why the hell is my bathtub in constant need of new caulking?....and I've always used the "biocide" bathroom caulking around my tub.

That being said, I will report back on the progress of the tank. It's a 20 long Metaframe, with the silicone being used as a precautionary step. I didn't want to trust 40 year old sealant to hold off 20 gallons from my hardwood floors.