Condensation or tank leak?

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Aquarium Advice Newbie
Aug 28, 2007
I am getting ready to set up a 50 gallon tank that was given to me. The previous owner is a close friend who would have said it had a leak if he'd known it.

I bought everything to get the tank set up and was planning on doing that this week.

A gut feeling said I'd better put a few gallons of water in it before I went and set the whole thing up.

I had my husband take the tank outside to the porch. When he set it down, he had about a quarter size spot of water on his pants. The tank LOOKED dry when he took it out. The stand didn't show any signs of being wet. The tank did get a little rain in it when it was being transported so when we got it and put it on the stand it did have just a very small amount of water in the bottom. It has been sitting on the stand for about a week already without my adding any water to it at all and the inside looked dry. I figured that if there was a leak the water would have gotten the stand wet.

So last night I added two gallons of water to just cover the bottom of the tank. I placed a towel under the place where the water had come from and got on my husband's pants. No sign of water on the towel.

This morning I dumped the water out and I noticed there was what appeared to be condensation, or like little spots of water under the seal and between the seal and the glass. I tipped the tank over when I touched the outside bottom of the tank there was enough water to just wet the tip of my finger. I don't know if that was coming from the tank, or if it was from where the water got on my husband's pants, or if the tank has a leak.

I'm hesitant to set up the tank until I know if we need to replace the seal.

Can I just add the sealant to the underneath of the tank to reinforce the seal on the inside and then try adding water again?

We brought the tank inside and are going to let it completely dry. Then take it to the garage and place newspaper under it and put a couple of gallons of water in it again.

I'm really getting discouraged because I was really ready to get the tank set up and start the fishless cycle.

Any help and suggestions would be greatly appreciated!

50 gal
EMPTY right now!

1.5 gal
2 male guppies
1 pearl snail
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Welcome to AA! I would try first adding some sealant to the tank. The moving of the tank may have broken open a seal. The only way to know is to try resealing the outside and then filling the tank with some water and testing it. I would use newspaper underneath the tank and on top of the towel should tell you where if anywhere it is leaking. If it is leaking you will have to clean off all the old sealant and reseal the entire bottom of the tank.
If you see wateer between the seal and the glaxss, you should strip all the silicone out of the inside, and reseal. Patching over old silicone is asking for trouble. Better to fix it now than have to tear it down to do a repair later. Lots of people recommend filling tanks outside, but unless you have a perfectly flat spot to put it, you are, again, looking for trouble. If a tank is filled on an uneven surface, it could cause a leak or the fracturing of the tank.
Really, resealling a tank is not that difficult, and you will have the peace of mind of knowing, you will have years of trouble free use from the tank.
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