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Leak Testing an Aquarium

Checking an Old or Used Aquarium for Leaks

(The First Tank Guide)

Why Would I Have to Check an Aquarium for Leaks?

When you bring an old aquarium out of storage, when you prepare to convert an aquarium back from use as a terrarium or small animal cage, or when you prepare to set up an aquarium you purchased used, it is important to check to see if the aquarium leaks. Checking for leaks before setting the aquarium up can prevent significant damage and losses.

How to Check an Aquarium for Leaks

In most cases, checking an aquarium for leaks is rather simple and straight forward, but like many things related to setting up an aquarium, it requires some patience.

First, you will need to have a good location to test the aquarium. Your location should be level, flat, and should not be someplace that can be damaged in case of a leak. Usually a garage, patio, or driveway will work very well. In many cases, you can just set something up in your yard.

Then you will need to get some kind of functional stand for the tank. The stand does not need to be decorative, but does need to eliminate any irregularity in the surface you are setting the tank up over, and does need to support the weight of the tank and water. If you are setting the tank up to test on a hard, solid surface that will not absorb water or hold moisture, your aquarium stand will probably work just fine. However, if you are going to do your testing over soil, or something that may have a possibly irregular surface, something like cinder blocks or bricks and planks may be a better choice. Just remember that this must be strong enough to support the weight of the tank and water!

Once you have a location, and have your tank set up on your temporary stand, fill the tank about 1/4 full of water. At this point, you should not need to dechlorinate the water, nor should you have to pay particular attention to the water temperature - you will be disposing of this water in a few days without ever introducing fish to it.

Once you have the tank about 1/4 full, dry off the outside and let the tank sit for at least 24 hours. Return and check for any leaks. If the tank is leaking, then you will need to decide whether it is worth trying to repair the tank, or if you are better off just getting a new tank.

If the tank is not leaking after 24 hours, then you should about double the water volume in the tank. Now that the tank is about 1/2 full, again let it sit for 24 hours or more and check for leaks again. Again, if the tank is leaking, you will need to decide whether you want to see about getting it fixed, or just getting it replaced.

If the tank is still not leaking, increase the water volume by about 50%, so the tank is about 3/4 full. Again, let the tank sit for 24 hours of more and check for leaks, and, again, if it is leaking, you'll need to decide whether to try to get it fixed or to just replace it.

However, if the tank is still not leaking, finish filling the tank and again let it sit for 24 hours or more. If it's leaking, again, you'll need to decide whether to get it fixed or get a new one...

If the tank is not leaking after it has been full for 24 hours, it is probably safe to set up (there are conditions where a leak will show up after several days, so you do want to be aware of this, and just because you have gone through this procedure does not guarantee that the tank won't leak in the near or distant future...).

If the tank is not leaking, drain it and dispose of the water. You should now be ready to set up your aquarium.

Why Take So Long to Test the Aquarium? Why Not Just Fill the Tank and Check for Leaks?

There are many reasons to take your time while leak testing an old or used aquarium. In addition to Patience is a virtue, here are the first few that come to mind:

  1. If there is a significant leak, filling the tank slowly will let you find this leak without making as much of a mess.
  2. If there is a structural problem with the tank, filling it slowly will let you find this leak with less likelihood of the tank breaking.
  3. Taking time to go through this process makes it more likely that a slow leak will be found before you set the tank up inside where a leak can do a lot of damage.
  4. Slowly checking the tank will give you more opportunity while you are waiting to check your books and other references and make sure you know how to get everything set up, and will give you more opportunity to research what kind of fish you wish to purchase.

Is There Anything Else to Be Concerned About when Leak Testing My Aquarium?

Well, first, as I mentioned above, even if you go through this process, it is still possible to damage the aquarium when you move it into your home, and it is definitely possible that the tank will eventually spring a leak. It is also possible that the tank has a slow enough leak that you will not have noticed it over four days, so it is very important to continue to keep an eye on your aquarium and check for leaks regularly. Slow leaks can eventually become fast leaks, and the sooner a leak is caught and repaired (or the tank replaced) the less likely it is to become a major problem, or to cause significant damage.

You should also make sure you are setting your tank up to test where it is not likely to get pesticides, detergents, or cleansers dumped into it, as these can leave residue that can stay in the tank long-term and can be very hard to remove, and may have long-term effects on your fish.

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