Tropical Fish Forums

[dale]

Here is an old breeding tank I have. It has a crack in one side panel (repaired) but it still is servicable. The problem is that it has housed reptiles and the silicone is clawed away in several spots. Time to re silicone!



I usually use a combination of chisel and razor blade to take off the old silicone. The chisel takes off the bulk and the razor peels away the little bits left behind. When I do a tank I strip all of the silicone built up inside the tank but not the thin layer actually sandwiched between the panes of glass. This thin layer gives the tank its structural integrity (strength) and should rarely deterioate. I never mess with it. It is the silicone built up along the corners of the glass (the stuff you can touch inside the tank) that provides the waterproof seal. All of this must be replaced. Trying to leave part of this lining in place and repairing around it may create a weakness in the waterproof seam.



Take your time and be thorough when stripping the old silicone. Any little left behind bits may create a weakness in the new silicone bead. After stripping all the old silicone I wash the tank out carefully to get rid of the little cuttings and flakes. Let the tank dry out overnight to ensure there is no moisture as this will cause the new silicone to not bond with the glass.

Here is a stripped, washed and dry tank, ready to go.



I use painters masking tape to line all of the beads I am running. This will create a smooth, professional look to the silicone when it is peeled away later.



Make sure you buy a brand of 100% pure silicone that is aquarium safe. Newer brands have mildew inhibitors that can be toxic. This information should be listed on the side of the cartridge.

First I run the bead around the entire bottom of the tank. I try to make this one long uniform bead but with the masking tape edging it isn't as critical. Any left over silicone will lift away. It is better to add to much rather than too little as you don't want to have to go back to fill in any low spots once things begin to tack up.



After the bead is run I smooth it with my finger. I am looking for a continuous run from corner to corner. My finger naturally gives the bead its concave shape and squeezes any air bubbles out. I always have a large rag or towel close by that is expendable to wipe my fingers on. All touch ups have to be done now, while the silicone is wet. Don't try to touch the bead once it is tacky or you'll ruin the bead.

After doing the bottom I flip the tank on its sides and repeat the process.



Once the siliconing is done the masking tape is stripped away to leave a straight edge to the bead. In the winter I have time to do the whole tank and then remove the tape but in the summer the silicone tacks up faster and I have to remove the tape very quickly (after the bottom) (after each side). Leave the tank alone to cure for 24 - 48hr's before water testing..




That's it!
I hope this helps anyone who is considering doing a re silicone job of their own.
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Intelligence is not having all the answers; it's knowing how to think!

[Marcos Avila]

Excellent as usual Dale! This is worth a permanent article...
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Success with a fish/tank is measured in YEARS, not months or weeks...

[Dusko]

O man I love those illustrated articles!!!

Fair play to you Dale nice work.

Regards, Dusko.
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[dale]

Thanks all!

I'll post a pic of the tank "in operation" soon (I hope ).
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Intelligence is not having all the answers; it's knowing how to think!

[lilmum79]

Very nice. I have a pair of gerbil sisters in a 10 gallon that are getting on in years. I was wondering what my options were for the tank should I lose the gerbils (god forbid... I love those girls). This looks like the perfect guide for me. I was thinking about setting up a breeding tank separate from the quarantine tank. Thank you very much for sharing.
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swimming pools are just fish bowls for humans... not very stimulating

[xcooperx]

Perfect Article I love it, I have a question what about the sides of the tank how you apply the Silicone are you gonna put it while the silicone at the edge corner is wet or it should be dry?
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[dale]

I apply all the silicone at once. I do this to avoid any potential weaknesses (between the dry and wet beads) and because I have found that, once opened, silicone tubes often dry up and are hard to reuse.
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Intelligence is not having all the answers; it's knowing how to think!

[Angry Andy]

Excellent DIY article, Dale.

Two things I'd suggest doing differently amongst the procedures:

-doubling the bead size for applying silicone to the base of the tank, where most of the stress is absorbed

-using skin-tight latex gloves when spreading out the bead with your fingers


What do you think?

[dale]

The silicone bead that is applied as per the article does not play an important role in holding the tank together; that job is performed by the thin film of silicone actually sandwiched between the panes of glass so increasing its size won't really improve the tanks integrity. For water tightness it is far more important to have very clean glass and a smooth continuous bead with no air pockets than a large bead.

Some people react badly to silicone but I never have. I have recaulked hundreds of tubs as part of my job and have always used my fingers. I find gloves reduce the sensitivity of my touch and I rely on those subtle cues. To each his/her own though
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Intelligence is not having all the answers; it's knowing how to think!

[McP]

Great article Dale!

I've tried using Silicone with and without using gloves and found that you just can't get the feel with gloves on nearly as good. The glove sticks or slips and I end up just going bare hand in the end.

Also just for the sake of repitition, make sure you are using a silicone that is 100% pure silicone. Beware of any new and improved claims as usually that means theyve added something like one of those lovely anti mildew chemicals