Silicone in the Aquarium Hobby

[SometimeSage]

I have recently begun experiencing the breakdown/decomposition of silicone items around my house. It's gotten me thinking about the silicone seals we rely on so much.

Somewhere around the 9 year mark, the silicone items in my kitchen start to become extremely oily. They pick up tons of debris. No matter how well I wash the oil off, it just reappears the next time I go to use it. Within two years the item becomes extremely brittle and fails.

The age of the silicone items failing in my house is very close to the recommended 10-15 year lifespan for an aquarium. However, I have never experienced aquarium silicone getting oily and overly sticky. One of the LFS's I worked at had an ancient slate bottomed tank, the silicone was brittle & delicate but not greasy.

1) Are there any signs, other than leaks, that your aquarium silicone has gone bad?
2) Do you think the lifespan recommendations are bogus or legit?
3) Would it be good practice for us to tear down our tanks once a decade, just to refresh the silicone?

 

[FJB]

I am not an expert but this is my experience. The degradation described can occur over time in many types of “rubber” items (quotes to indicate a variety of materials, included silicone, rubber and some plasticized items), particularly in unfavorable conditions such as high heat, or exposed to leftover soap or other chemicals). It is not just due to age.
I have seen this in silicone in tanks and other items left for years in a hot garage or outside. But I have never seen in an aquarium in use, regardless of age.
Regarding the questions-
1) if sticky, it is suspect but not necessarily gone.
2) I don’t agree much with lifespan recommendations, which depend a lot on conditions anyway
3) If a tank’s silicone looks and feels good, it does not leak when filled for extended periods of time, and there is no evidence it has been empty in unfavorable conditions for extended time, then no, there is no reason to assume it is bad because it is 10 years old. That one may want to reseal it because one does not know the history of a used tank one is acquiring….that is another story.
Heck, ALL my glass tanks are more than 10 years old, some certainly double that or more.
These are guidelines to myself. I would not push them onto anybody else.

 

[esoxlucius]

I'm far from an expert on this either but I see it this way. When comparing your "round the house" silicone with aquarium silicone you aren't really comparing apples with apples.

Round the house silicone is exposed to all sorts of stuff in its lifetime, stuff which aquarium sealants would never come into contact with. And a lot of this "stuff", in time, has an adverse effect on the kitchen and bathroom silicones.

I remember starting a thread years ago now about at what stage in an aquariums life do you reseal a tank, whether it still "looks" ok or not. Not strip it down completely, just reseal it. I think the common concensus is 10-15 years, for peace of mind.

But then there is also the other side of the coin where hobbyists have had tanks running for decades with the original silicone. I think it's one of those subjects where there isn't a standard across the board solution.

 

[12 Volt Man]

I setup my Aqueon 150g in December 2008 and the seams still look excellent <touches my wood>

I am probably going to swap the tank out I figure at the 20 year mark or thereabouts.

 

[Lepisosteus]

That sticky feeling on rubbery items can be removed with a baking soda slurry. Just mix baking soda with a bit of water into a thick paste and scrub it. Takes years to come back.

As for aquariums, when the silicone becomes flaky or you can peel it from the glass it’s time to change it.

 

[cockroach]

Also, not an expert here but my thoughts come purely from using silicones and having many aquariums for many years.

a. The type of silicone used for kitchen use has to be food grade and is heat/freeze resistant to high/very low temps. Aquarium silicone is more akin to an industrial application and is 100% silicone. It cannot withstand huge temp differences.
b. The smell alone is a dead give-away. I have seen people mention aquarium silicone being fine for incidental food contact whereas silicone cookware is by design meant to be in contact with food.
c. As for shelf life. I have yet to see a silicone kitchenware item last its expected duration. This is most likely due to the heavy/extreme use and hard chemical cleaning. Aquarium silicone on the other hand has often outlasted it's "best before" date by a country mile. I have an aquarium I bought 19 years ago. It is still going strong after earthquakes and high summer temps. I feel the humidity here helps with the longevity.