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I bought a used 55gallon tank for my lil guys and there seems to be some algae under the old caulk. I'm guessing it may start leaking so I thought I'd redo it myself if possible. Can I use regular silicone or do I need a special kind?

i would use aquarium silicone. that way you know it wont harm anything

All-Glass sells small tubes of the stuff as well. It should be handy for minor touch-ups.

If you have marine supply shops around you, they should have submersible silicone in the large cartridges (most of the "regular" stuff in hardware stores can't even be used underwater). You would still have to read the fine print to make sure it is aquarium safe.

G.E. Silicone I is safe for aquarium use. Make sure it's I and NOT II. Also make sure to get the window and door version. The kitchen and bath version contains a mildewcide that is harmful to fish and turtles. I've used this stuff many times to re-seal aquariums. Read this article if you don't know how to do it: http://albertaaquatica.com/index.php?showtopic=11713.

I don't know about Silicone I. The Home Depot around here told me that GE retracted their statement that it was aquarium safe, but they didn't know the details on why GE did it.

But I do know that many people have used it in the past without problems, so I would be interested to know why GE retracted it.

Or perhaps GE never did say it was aquarium-safe, and all they did was tell Home Depot to stop claiming it was, just in case legal issues arose.

I think it was retracted for legal reasons -- might have been that they couldn't guarantee the strength. I've also heard it's the same stuff they use for All-Glass, but you never know.

can you use regular sealent on the outside of the tank.

i got my eye on a tank with a crack in the base.

the idea was to build a base for it to stand in then fill the stand full of sealent then stick the tank in. thus creating a complete seal over the entire base of the tank.

blulite wrote:can you use regular sealent on the outside of the tank.

i got my eye on a tank with a crack in the base.

the idea was to build a base for it to stand in then fill the stand full of sealent then stick the tank in. thus creating a complete seal over the entire base of the tank.

Even with sealant I wouldnt use anythign with a crack in it unless your only putting like 2" of water in it but even then your almost certainly asking for it. You may however be able to strip existing sealant an replace the panel.

Or make it into a non-aquatic reptile setup.

the idea of relpacing the panel was a last resort. the crack is not major and when filled the tank hardly leaks. probably not more than a cup a week if left that long. if i can figure out a way to keep the water in without replacing the pane well thats good enough for me.

if you guys will picture this!!

a custom built base 4 inches deep. the inside measurement of the base = the size of the tank.

the tank will sit 3 inches into the base without any sealent.

i pump approx 1-1.5 inches in depth of sealent into the inside of the base covering the entire area.

now i sit the tank in and give it a push so it adheres the entire bottom area to the sealent. let it dry and hey presto SHOULD be water tight.

i believe this will work as ive heard it to be done with small tanks but not with big ones

its worth a try i suppose. if it dont work then i can dismantle the base and change the pane.

however is it possible to use none aquarium sealent as it is going to be an external repair (maybe, if it works)

I would put the sealant on the inside of the tank, so that the water pressure is pushing the silicone into the crack instead of away from it. I have a 75 gallon with a cracked bottom which is now filled all the way to the top. I used Starbrite Marine Sealant and slathered on a six-inch-wide patch, roughly a quarter inch thick at the crack. It slowly tapers off to meet flush with the glass roughly three inches from either side of the crack. I did this with the tank on the stand, and it will never be moved. If it does get moved in the future, I would strip everything out and reseal it.

@ squishy

the base which i am planning means the sealent will be sandwiched between a piece of 3/4 ply and the externals of the bottom pane whats your views. what abotu sticking a piece of perspex plastic inside the tank on a bed of sealent. obviousley the full area of the tank

I would still seal the inside instead. It will be hard, if not impossible, to distribute or eliminate air bubbles inside the sealant so that the tank is equally supported throughout the base. You may have more bubbles in one area, making it more flexible and unable to support the tank.

Putting a piece of plastic inside the tank and completely resealing the tank with the plastic in place is almost guaranteed to fix it, but for the cost of a sheet of acrylic to line the bottom, you can probably find a used tank on craigslist. That is why I decided to take the risk of only using sealant to fix the crack. You would not need to put the plastic down on a bed of sealant - simply seal the seams as you would normally. If done correctly, no water will even touch the bottom glass.

If you do fix it, I would remove the bottom plastic trim and have the base glass rest directly on the stand, supported by a sheet of corrugated plastic/cardboard.

I would go with what Squishy did.