can silicone caulk be unsafe?

[Viktor Jarikov, posts: 2276]

For my 2500 gal indoor pond (in my basement), I've been putting together an alternative filter using a regular 96-gal gardage toter (from Lowes home improvement store). The plumbing guy at the store appeared quite experienced and taught me how to put in inlets and outlets in the toter cheaply, safely, leak-free. He also gave me a few caulk-gun tubes of a silicone caulk that he said is the stuff used for sealing aquariums and designed to handle water pressure. It is 100% silicone for permanently waterproof jobs, exterior, interior, kitchen, bath, plumbing, etc. The brand is GE Silicone II (3 hour rain, shower, etc. ready; cures fully in 24 h). I trusted the store guy and read the instructions on the caulk tube too quickly. After I had spent the entire day putting in a 3" ID outlet at the hard-to-reach bottom of the 4-foot high toter, a 1.5" inlet at the top (for a 2000 gph submersible pump), and a 1.5" overflow outlet at the very top, I (for some reason) stumbled upon the last line in the directions field: "Not for use below the water line, where FDA (food and drug administration, USA) compliance is necessary, or aquariums". Man!!!!!!!!!!!!!!!!!!!!!!! Am I to start buying and rigging over again? It is a good chunk of money, time and effort! Any well-grounded or better yet experience-based opinions out there?
Thank you in advance.
Viktor

[Viktor Jarikov, posts: 2276]

please see also my question about plastic pot scrubbers (I intend to use as a filter media) at viewtopic.php?f=4&t=24141
Viktor

[alga, posts: 67]

I'll take your concerns in backwards order. The scrubbers are fine as long as that's all they are. Some have soap already in them, just be careful. The silicone you mentioned is the one I think most people use but my concern is what you are attaching to make these inlets and outlets. When you are talking about the this much water you probably should invest in bulkhead fittings. The big reason being is that over time silicone will stop adhering to plastic and then it will start to leak. It may be a couple/few years down the raod but eventually it will leak.

[MatsP]

I'm 99% sure that the one you want is GE Silicone I (roman numeral 1) not GE Silicone II (roman numeral 2) , as although it says 100% silicone, it's a lie - there is a small amount of anti-mold agent in the 2 version, whereas there is none in the 1 version.

And I just double checked: GE Silicone I is the one you want to use.

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Mats

[alga, posts: 67]

Eventhough you found the one to use, I would not use it to seal plastic to plastic, it will eventually leak.

[Viktor Jarikov, posts: 2276]

to Mats: thank you! ok, so the conclusion is next time I will use GE Silicone I (one). But: (1) can I use what I've made with Silicone II (two)? (2) If not, why not? will the anti-mold agent kill beneficial bacteria or will something leech out of the caulk and affect my fish's health or something else?

to alga: thank you! The plumbers I asked around had similar concerns, some more, some less, some didn't. The bulkhead 3" ID is around $200, not a showstopper but ouch! What I rigged looks like this viewed sliced and starting from outside of the toter: 3" ID hard PVC male adapter (slides thread-first into the hole in the toter) | three gaskets cut out of 45 mil (1/8") rubber pond liner | toter wall, hard plastic, about 1/4" or thicker | three large area gaskets, much, much larger than the 3.5" hole, cut out of the same pond liner | same large area acrylic plexiglass "washer", thick, 1/4" | female 3" ID hard PVC adapter screwed onto the male's thread (presses the washer and the inside gaskets to the wall). The Silicone caulk in question is applied between ALL the surfaces in the above row, including between the layers of the gaskets and all around the outside of the gaskets and the "washer" and around the male and female adapters in a very thick layer. Tightened well with a strap wrench (bicycle chain wrench rather). After all this, you may be still right - it may leak now or later but for great many reasons, not the least of which is that this is my first time putting together something like this using the plumbing stuff not designed for this.

[alga, posts: 67]

Wow. After reading through the amount of materials and silicone you must use (between each layer) I am guessing it's hard to keep it "nice looking. I searched a few pond type places and found 3 inch bulheads for between 20 and 70 dollars.

[MatsP]

All advice I have found so far indicates that the anti-fungal (fungicide, anti-mold, whatever you call it) is not good for the fish.

If you have, say, an external joint using this silicone, I would just put the "good stuff" on the inside of the tank. But on the inside, I would definitely recommend cutting it out and re-applying the good stuff.

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Mats

[Viktor Jarikov, posts: 2276]

Mats, the wording on the tube of GE Silicone I (one) is slightly different from that on GE Silicone II (two) but still unsettling. The last sentence of the instructions reads: "Not for use below the water line or aquariums." Do you think this can be disregarded? Do you still assert that Silicone I is the way to go?

[MatsP]

If the Silicone I (one) also says not to use in Aquariums, then I do not know what to say. If you search the web for something like "GE Silicone for aquarium", everyone says Silicone I is the one to use, and the Silicone II (2) is not to be used in aquariums. Of course, sometime companies change the formulation.

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Mats

[Viktor Jarikov, posts: 2276]

Okay. Can it be that there exist different types of GE Silicone One, made for pet shops and for hardware stores? And can my mistake be that I went to the home improvement/hardware store (Lowe's) to get theirs? Here is a small piece from e-how:

http://www.ehow.com/facts_5892414_kind- ... rium_.html

Safety. Silicone sealants sold in pet stores or aquarium supply shops usually have safety labels. These sealants will not leech chemicals or degrade in the water and are generally safe for freshwater and saltwater tanks. Sealants sold in hardware stores might not specify their safety for fish tanks and could contain toxins.

[Viktor Jarikov, posts: 2276]

another small piece: http://www.corals101.com/Information/Aq ... esives.htm

Attaching glass to glass

There are other adhesives that you use on your aquarium before it is filled with water. One of these is called the silicon caulk. Typically this is used to seal cracks in the glass. It is needs contain 100% silicon caulk, and nothing else. The thing you want to watch out for here is make sure to aquarium safe because some silicate silicon caulk has a anti-fungal agent put into it, so that when you caulk your outside door or window, mold wont grow on it. This additive is toxic, so don't use caulk that contains it. We have used a product by General Electric, called GE 012 in the past successfully, but arent going to warrant that it is safe. Try it at your own risk, but we havent had any problems with it.

Silicon caulk is very useful for either making any a glass aquarium from scratch or even repairing a glass aquarium. It is quite easy to work with, and you can trim it with a razor knife and and then once it cures, silicone caulk is inert and will not harm inhabitants in the aquarium. Don't put underwater until it's completely set up and cured. And certainly, you don't want to put any pressure on it until its's cured either, such as filling up the aquarium, because caulk only has limited ability to withstand a load stress

[Viktor Jarikov, posts: 2276]

another site that appears to be highly edifying
http://www.aquarium-pond-answers.com/20 ... icone.html

[Viktor Jarikov, posts: 2276]

this forum is quite confusing: some people say any silicone is fine, others argue against it
http://forums.gardenweb.com/forums/load ... 22511.html

[Viktor Jarikov, posts: 2276]

ok. I have just gone to the LFS and got two tubes of Marineland 100% clear silicone rubber, fish safe, meant for aquariums, handles water column pressure. Sure it is 2-3 times more expensive, $12 for a standard caulk-gun sized tube 304 ml or 10.3 US fluid oz, but if I knew it from the get go, I would not hesitate to use just that. So far, I have not found silicone in a general home improvement store whose label would state "aquarium-safe" or some such thing.

[MatsP]

this forum is quite confusing: some people say any silicone is fine, others argue against it
http://forums.gardenweb.com/forums/load ... 22511.html

Well, that is of course the WWW for you - there are always SOMEONE that has a different opinion or experience. And it MAY well be that the fungicide isn't harmful to fish or aquatic creatures. But betting on that is perhaps not the best choice. There are silicone products out there that do not contain fungicides - at least the ones produces specifically for the aquarium industry. I'm sure there are OTHER products too.

I'm pretty sure GE doesn't produce a product with their name and label that is called the same thing specifically for aquatics stores - the stuff you find in Lowe's, Home Depot, etc, should be exactly the same stuff that you get from any other store that sell the same thing. If you want to make absolutely sure, check the bar-code number. If it's the same number, it's the same product. [However, beware that manufacturers sometimes "improve" their product - I recently noticed the label on the curry paste I use for cooking curries was different. It turns out that they have "reformulated it" to make it more "healthy" - less salt and less fat. Doesn't taste at all the same either. But the bar-code number is the same!]. What I'm trying to say is that if they have two similar products for different markets, it has to have a different bar-code so that the manufacturer and seller can tell the difference. But what is for sale today as product X may not have the exact same ingredients as product X from a month or 5 years ago, because the manufacturer decided that they could make it "better" in some way.

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Mats

[MatsP]

ok. I have just gone to the LFS and got two tubes of Marineland 100% clear silicone rubber, fish safe, meant for aquariums, handles water column pressure. Sure it is 2-3 times more expensive, $12 for a standard caulk-gun sized tube 304 ml or 10.3 US fluid oz, but if I knew it from the get go, I would not hesitate to use just that. So far, I have not found silicone in a general home improvement store whose label would state "aquarium-safe" or some such thing.

There was some discussion on some other web-site that the lack of "aquarium safe" labelling on some product is simply "lawsuit avoidance" - meaning if the product doesn't say "you can build aquariums with this", you can't get sued by idiots that don't realize that 1/2" glass isn't thick enough for a 8' x 3' x 3' aquarium ...

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Mats

[bronzefry, posts: 2198]

Victor,
I use the Marineland stuff. It works well. Expensive, compared to the others, but it does the job.
Amanda

[Viktor Jarikov, posts: 2276]

To Amanda: Thank you!

To Mats: Thank you for the tip about the barcodes, Mats -- why is not anything easy? Oh, yeah, right, right... I keep forgetting that it's a fallen world . The reason I said what I said about GE silicone is that even within one home improvement store there are differing kinds of GE Silicone I and differing kinds of GE Silicone II: some are geared towards windows and doors, attics and basements, others towards kitchen, bath, plumbing; yet others have eye-catching labels about 5-year mold-free protection while the rest are silent about that. I have not looked at ALL of them but those say 4-5 types I read intructions on the tubes carefully, ALL say "Not for use below the water line or aquariums".

To Alga: thank you! you are right, there is plenty of sources selling bulk heads in the price range you indicated. I have no idea why Ferguson Plumbing guys sell 3/4" ones for $80 and 3" ones for over $200. Must be some fancy shmancy stuff for a different application. Anyway, I ripped my "masterpiece" apart and ordered bulk heads from "123ponds" on line.

Bottom line for me: before investing money, time, and labor - research and do not trust "professionals" you find at the stores. More specifically, for rigging ponds go to pond stores! Duh!!!!

[alga, posts: 67]

Chart this up to another discussion forum success! Great input from all and I can't wait to see some pictures Viktor.