Resealing a Tank

ReeferWarrant · Feb 25, 2020

So I found a tank with a leak for sale, and if it works it's an upgrade from my current setup. Anyone have experience resealing tanks? The leak is at the base of the tank in a corner. I've watched YouTube videos on how to reseal and it doesn't look too difficult. Just hesitant to risk a large amount of water flooding our basement.

jwshutt · Feb 25, 2020

When I got my 90 gallon almost 2 years ago I didn't do a leak test on it and started putting water in it. Found out at about half full that there was a slow leak in the bottom back corner. Emptied the tank of all water, sand, and rock. Then took a razor blade and removed the old seals from inside the tank. Had to be careful not to dig too far into the seam or else I would have had the tank come apart on me. Got some aquarium silicone from my LFS and put a bead along all seams; bottom and sides. Once I had bead on the seams I then just used my finger to smooth it out. Let the tank air dry for 48 hours and then did a leak test on it. Everything was good to go. Haven't had any issues whatsoever. There are lots of youtube videos and online articles describing how to reseal. Just make sure you let the silicone fully cure before adding water.

ReeferWarrant · Feb 25, 2020

Awesome! Yeah, if I go forward with it I'll still have my current setup going. So you don't have to completely remove the seams as well?

That's what I was afraid of. I have a Biocube 32 (a great beginner tank) and I hate the lower intake grill that it has, my bicolor blenny keeps trying to back into the slots... The one I found is an Innovative and it only has the upper intake. So an extra 8 gallons and removing something I cant stand about the Biocube might be worth it.

vetteguy53081 · Feb 25, 2020

Scrape away old silicone 100% and clean with alcohol as a clean oil free glass will offer the best adhesion and sealing success.

steallife904 · Feb 25, 2020

how big is this tank? If its smaller, say under 90 I think I would be ok with doing the above. Bigger...… I would be to afraid of it exploding one day with the amount of water pressure involved with a big tank.
Removing the silicone inside the tank and re siliconing it could work for stopping the leak and im sure be fine on smaller tank but if its leaking water through a seal then the silicone holding the panels together is somewhat compromised. That would be a weak spot. That's why I say on a larger tank idk. This is all just my opinion and I cannot say I am absolutely correct so look for others to advise as well.

ReeferWarrant · Feb 25, 2020

Yeah it's only a 40 gallon, and exactly why I have been hesitant with it. I figured if the water is coming out the seal on the glass is compromised like you said. Absolutely, all of the LFS people I have talked to were immediate "No" because they didnt want any liability. I understand I'm taking a complete gamble with this option.

steallife904 · Feb 25, 2020

well with a 40 I would probably be ok with doing it because its not as much water volume/pressure. On the flip though a 40 isn't to expensive so is it really worth it instead of just getting a new one?
I can tell you if you do re seal it you will think about it everyday

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Super Fly · Feb 25, 2020

if it'll keep u thinking about it afterwards, then IMO not worth it and I wouldn't bother.

nereefpat · Feb 25, 2020

steallife904 said:
if its leaking water through a seal then the silicone holding the panels together is somewhat compromised.

Yep

ReeferWarrant · Feb 25, 2020

All good points, I'll just save up for the upgrade then. Unless he drops it to being really cheap and then I'll do it for fun.

Slawman · Feb 25, 2020

Silicone will not bond to itself which means that any repair cannot rely on that. This basically means that you need to strip all the silicone off all the glass mechanically and start over. Not worth the trouble and risk in my view, tanks are cheap and water leaks can be expensive...

scottedontknow · Feb 25, 2020

NO NO NO NO NO NO NO NO NO. If a tank is leaking that means the seam is already bad. removing silicone from the corners and just adding new HAS ZERO effect on the strength. to reseal a tank the correct way you MUST remove the top and bottom brace (if you have one) then remove ALL silicone and take apart the entire tank, then you have to sand and buff all the edges to then finally re silicone EVERYTHING. just adding new silicone to the inside will only buy you a bit of time but it WILL fail maybe a week or could be a year or two but it will 100% fail (depends on where the leak is on the tank) but in your case a bottom leak is the worst. i would recomend NOT buying the tank unless you plan on doing it the correct way.

Billdogg · Feb 25, 2020

scottedontknow said:
NO NO NO NO NO NO NO NO NO. If a tank is leaking that means the seam is already bad. removing silicone from the corners and just adding new HAS ZERO effect on the strength. to reseal a tank the correct way you MUST remove the top and bottom brace (if you have one) then remove ALL silicone and take apart the entire tank, then you have to sand and buff all the edges to then finally re silicone EVERYTHING. just adding new silicone to the inside will only buy you a bit of time but it WILL fail maybe a week or could be a year or two but it will 100% fail (depends on where the leak is on the tank) but in your case a bottom leak is the worst. i would recomend NOT buying the tank unless you plan on doing it the correct way.

^^^This^^^

x 1,000,000,000,000,000...…………...

The inner silicone caulking is ornamental in nature only. It's primary function is to make cleaning the corners easier. The actual seal is the small amount of silicone that is between the individual panes.

Resealing a tank is a major undertaking if you have never done it before. Because the glass box is one of the least expensive things in this hobby, and the cost of repairing the damage - to your house, to your relationship with your SO - is so high, I wouldn't even try.

jm.02

Cory · Feb 25, 2020

If you take apart the tank take off excess silicone with a soft wire wheel brush and drill. Would have saved me days on my 220 if i knew that before! It doesnt scratch the glass either.

ca1ore · Feb 25, 2020

As others have noted, a leak means the structural seal is compromised. A reseal may well stop the leak temporarily, but a compromised structural seal is a ticking time bomb.