Used empty tank

[Nighty]

How long can a used tank - say, a 72 gallon glass Oceanic - stand empty?  I've heard a few horror stories about used tanks rupturing or leaking ...

Mildly paranoid,

Nighty

[Marc]

In my opinion, many years.  The only thing that can go bad in an empty tank is the silicone and silicone takes many years to go bad.

Silicone used around your bathtub will last more than 10 years and will usually be changed because of mold on it, not because the silicone went bad and caused a leak.  The silicone in an empty tank, is not exposed constant humidity and is not exposed to sunshine so it should be good at least 10 years, probably more.

Marc

[spotted_gecko]

I agree, i've had 20 gallon tanks dry for years, their used and then drained out again.  As long as you wipe it down after you drain it you shouldn't have a problem, obviously test it before you fill it up again, but if it leaks just go to the petstore and buy some aquarium silicone (stuff works great).

[Nighty]

Many years?  That's promising!  Thank you - I'll be downgrading my level of paranoia!

[saltydog]

My advice would be to test the silicone for signs of deterioration. Run your finger along it to see whether it feels "resilient".  If it does not then you might also see signs that it is no longer adhering well at the edges of the 'the bead'.  If this is the case it does not mean that the tank will leak but I would advise scraping all of it off with a rasor blade & applying new silicone. It is not difficult & will save a big headache someday down the road.  

Use your index finger to spread the new bead on the sides & your thumb on the bottom.  And if you want a "perfect" job, use  tape to mask the edges so the silicone bead is straight & not overly wide & messy looking. Remove the tape immeditately after each bead is applied as the silicone starts to cure very quickly. Use only slicone which says on the tube that it is safe for aquariums & let it dry for 3 days before filling the tank.

The above will replace the silicone that lines the tank to prevent it from leaking. It does not replace the "structural" silicone between the glass panes which is largely responsible for holding the tank together. When this lets go a tank will "blow", putting very nearly the entire contents of the tank onto the floor. This is why it is adviseable to fill an older tank slowly over several hours. Replacing the "structural" silicone is a job which requires that the entire tank be disassembled & rebuilt, which is much bigger job.  I have about 1500 gallons of 'used' aquariums chez moi & have never experienced this problem. However, I sold a 90 gallon tank to someone who experienced a 'blow-out" of the front panel the first time that it was filled with water.

[Nighty]

So if a tank has been empty for a year or so, you recommend filling it over a period of days?  Is this because the structural silicone of the tank 'stretched' when the tank was full of water?  Does it lose its resilience?

How do you know when the structural silicone is in need of replacing?  My tank is about five years old, bought when new, and has been empty for a year.  The sealing looks okay ... but I guess one never knows!

Regards,

Nighty

[saltydog]

There is really no way to test the 'structural' silicone. However, if the 'sealing' silicone seems "resilient" (& it is original) then the 'structural' silicone will be fine. In the case of a tank being empty for a long time I would think refilling it slowly over a couple of days would be prudent.

Best of luck!