So, I finally acquired a 55 gallon tank so I can begin the expansion of my sump/fuge project.

A question I have is... I have seen "aquarium" silicone in special packaging, and theres the good old caulking gun tubes of silicone.

My guess is they are the same... but...

Does anyone know for sure? The caulking gun tubes of silicone are waaaayyyyyyy cheaper... and more convenient... and they smell the same (like vinegar - wierd)...

But ARE they the same is the question.

I think that I read somewhere that you have to read the caulking gun tubes because some of them say "Not for aquarium use". But back in the 70's and 80's we used the caulk gun kind. :)

I wonder what the difference could be - once the stuff is dry I would think it's fairly inert. I will have to get by butt down to home depot and have a look, see if any of them have such language on them.

I remember hearing that normal silicone caulk used for windows and such has a fungicide in them, to help prevent the area around the windows from rotting overtime. My LFS said this fungicide could be lethal for animals if it leached from the caulk.

But i'm not sure how true this is, i often don't trust my LFS. But for what it's worth that's why i've been using the 'official' stuff even though it's a pain to use alot more expensive.

pain to use? You can buy AGA silicone in a caulk gun tube. Yes it is 2-3 times more expensive than good regular silicone but for all the other money that goes into your tank its worth the safety of the livestock.

I thought the gun was a little difficult to use in a tank, but you could try putting some into a plastic sandwich bag with a corner cut off and squeazing it out of that or some kind of cake decorator tool or a large syringe. That coudl make it easer to work with in tighter spaces, while still buying the larer volume discounted packaging.

I was thinking of the little metal 'toothpaste' style tubes that are like $8.00 that's the only ones we have around here... a gun tube would've been nice, i might have to find it online the next time i need some.

So look for the "AGA" type, huh.

From a thread elsewhere on the internet that I found while researching this issue...

GE 100% Clear Silicone GE-012A once said Aquarium Safe on the label. Why it no longer does is the source of urban legend. One says it's in deference to AGA so they can market the suff for 10x as much in lfs's since AGA uses literly tons of the stuff. Another says it because people would use it to build huge poorly engineered tanks and then sue GE when they broke. All I know is that it the 12A version IS aquarium safe, and available for a very reasonable price. I have used this stuff in the past and have it in my current sump. My understanding is this IS the silicone that AGA, Perfecto and Oceanic all use.

It seems that what sets one silicone apart from another is that one is Ammonia based, and the other is Vinegar based. And of course, we know why the Ammonia based version wouldn’t work.

It also seems that a tube of silicone that is Aquarium Safe is less likely to be specially labeled than one that is not.

So, I plan on hitting the hardware store later today and seeing what the tubes actually say. If there is a distinct aroma of ammonia or vinegar, then perhaps “the nose knows” when it comes to selecting the right product.

What does AGA stand for?

All Glass Aquarium, unless i'm mistaken... it's the brand name. But i think they changed there name recently to aqueon or something like that.

What does AGA stand for?

All Glass America.

I've emailed all the companies in the past to see what they had to say. Unfortunately I think their emails were lost when I moved and changed internet providers. But let me see what I found out.

One thing I know is that after all the correspondence I had with the silicone companies I now use only the "aquarium" grade. I don't remember why but will find out. I think the industrial version of RTV101 by GE is the product repackaged by AGA. I'll email everyone again and get back to ya.

But if I don't get approval for use of a non-aquarium based product in/on my tank I don't use it. Saving 50 bucks on overall costs of silicone is isn't worth my peace of mind. Think about how many inappropriate corals or fish we have bought for that price that died in our tanks.... pocket change really. I can't balk over 4 bucks for a tube of silicone when I have a 100 dollar fish or a 1000 dollar skimmer. I know I was interested in alternative sources of silicone because of it's availability. Sometimes aquarium silicone can be difficult to find... not all hardware stores carry it consistently.

Well, for starters silicone is not a cheap product to manufacture. It is actually quite expensive, due to it's durability and beacaue it is not permeable to anything we'd care about. The industrial grades of silicone are of poor quality. They're not meant to bind things together and hold them in place. Most industrial silicones are just meant to reduce moisture or air in unwanted areas; and to seam edges together. The tensile streangth of each grade varies, and as well with how flexible it is. The "aquarium" silicone, may very well be the same thing, or it could be of stronger caliber. I've never used it. But I have tried to peel silicone off smaller manufactured tanks and it really is hard to do. But if you take it off someone's home made tank, the industrial silicone can be peeled right off.
This goes without saying that, the surface should always be as clean as can be. Free of dirt, water, oil, anything that would interfere with it bonding to the surface. The cleaner the edge, the stronger the bond.
With this in mind, some have been successful at keeping large aquariums together with industrial silicone. I wouldn't recommend it to anyone over a 200 gal system. (Thats alot of pressure) If you do chose to go with a 'best guess" industrial silicone, make sure it is 100% silicone, does not have any other additives and requires a long time to kick, and eventually set. Like the hobby faster is not better. The longer silicone takes to dry, the stronger it will be.
I work with various silicone products, and...not go on for days I would not advise someone to purchase industrial grade for something they're going to be investing thousands in. It may not be as strong as aquarium silicone, clear silicone may sometimes yellow under water, or it may leach catalyst chemicals used to make the silicone kick faster. There is a reason, it is labled against aquarium use.

Here is the material safety data sheet for GE012A silicone rubber compound. Doesnt say anything one way or another about aquariums.

http://intranet.risd.edu/envirohealth_msds/PhysicalPlant/GE012A.txt

I called the GE number listed on that msds and they said that GE012A silicone - for that matter ANY of their silicone products leach ammonia during the curing process and are therefore not recommended.

Wonder how long it takes to cure?

I also called Aqueon (formerly All Glass) and they actually manufacture their own silicone in caulk gun sized tubes. The item number is 65010 for the clear, they don't do direct sales so they don't have a price. (of course.)

However I brought up my conversation with GE to them, and they said that ammonia will leech during the curing process of ANY 100% silicone product, but they become inert after cured. Crap man, I never had a clue that such a simple question had such a complex answer!

For the record, I work construction and have used caulk gun tubes of 100% silicone for aquarium repairs/adding skimmer boxes/sealing bulkheads/you name it for two decades. The odor, texture, and I'd wager my mortgage; the very chemical composition are no different than the product sold in a smaller tubes labeled "for aquarium use only." Cost isn't the factor to me; it's getting a good perfect bead right in the seam. With a caulk gun, I know the exact amount of pressure to apply to the trigger and speed to move the nose of the tube. Too much makes a sloppy job when you spread it with your finger, too little and you really need to wait for it to dry to re-apply more to the seal.
I'm far from claiming that I am a chemist, but I have successfully sealed more tanks than are in any LFS within 30 miles of me with 100% silicone in caulking tubes. I'd need some amazing evidence to change now.

I hear you. I am trying to remember what I used for my last sump project, but I would bet money it was the GE 65010. Worked great. Nothing has died. In fact I have so much LIFE in the damn thing that I am expanding to two tanks and the 55 sump.

But see I am the irritating guy that keeps asking questions until I get a definitive answer.

And it sure has been an interesting process thus far.

Cost isn't the factor to me either. I want the large size for the reasons you listed, and I want to make sure and use the right stuff so my lifestock is not adversely affected over the short term or long haul.

And silly me, I also like to understand WHY. :D

You can buy the AGA silicone in caulk gun tubes.

I was at home depot yesterday so I checked the silicone. All I saw was GE silicone I && II. The silicone II said mildew resistant. All said 100% silicone and in the fine print said not for aquarium use.

That's enough for me to pass it on by.

yeah... that GE stuff will yellow once submerged under water

Not to be argumentative, but I've used dozens of tubes from hardware and paint stores and none have ever looked even faintly yellow. I'm sealing an old 75 now using Sherwin Williams brand 100% silicone, will post pictures when it cures and I fill it up.
That said, I'd have bought AGA if I was aware of it being available in gun-sized tubes when I started. I'm not one to skimp on money with my aquariums, I made my choice simply because I am very handy with a caulk gun, and the squeeze tubes have proven very troublesome.

Well, maybe not all will yellow, but I've used the silicone I & II, and i dont know if its algae that grows on the silicone, or a chemical reaction that takes place but it yellows mighty bad.