All aquarists like to believe their aquariums will never leak, but the reality is that a leaking tank is just part of being an aquarist.  At some point during the years of owing aquatic pets, a tank has developed a leak.

Almost all commercially built tanks that use glass use a clear silicone sealant to join and waterproof each edge of a glass member.  When an aquarium is constructed a steel frame is constructed that is sufficiently strong so-as-to withstand the weight and subsequent pressure of a constant force pushing against the steel frame and not deforming it.

As with all manufactured parts, occasionally a frame is built that is slightly bent and does not allow glass to fit precisely.  Initially this causes no problems and the tank is watertight.  However, over time the edges of the glass permit the silicone sealant to bend and slowly pull away from the glass surface.  With an adhesion failure the tiny, barely noticeable, leak always becomes worse.

A leak like this starts with a damp area and may show rust on the aquarium frame.  As time goes on the leak will begin to drip and eventually it becomes clear that something must be done to correct the problem.

Leaks also occur as a result of broken glass.  While many will advise to just cover the crack with caulking sealer and call it a day, a glass fracture is comprised of what you see and what you don’t see.

Glass fractures are notorious for developing new fingers over time.  A glass fracture occurs when physical stress on the material finds a weak area and the weak area pulls apart.  What is seen is only the most obvious separations of material.  What is not easily seen are the many other micro-fractures that also occurred, but did not develop because the obvious crack relieved the stress the glass was under at the time.

Now that the glass has a new stress pattern, resulting from the crack, it will respond to new glass stresses by separating at the weakest points.  Unfortunately, those weak points are the micro-fractures caused at the time of the initial crack.

So, covering the initial crack with sealant will only be a short term fix.  The many other micro-fractures will eventually become visable and leak.  It’s better to either repair the glass panel by replacement, or invest in a new aquarium tank.

Just the thought of emptying the water and removing all the occupants can be overwhelming.  Don’t let this drag you down!  Relocating your aquarium to a temporary aquarium is not a big deal, just time consuming for an afternoon.

The process is surprisingly easy.  The first step is to move 33% of your existing tank water to the temporary tank.  Call it a hotel tank.  You can even make a paper banner and call it the RITZ!  In fact we will call the hotel tank the RITZ to differentiate it from the leaking aquarium.

With 33% of your existing tank water in place at the RITZ go ahead and fill the RITZ with 33% new water just as you would when performing a water exchange.  The RITZ should be 66% full at this point.  Check the water chemistry and adjust if necessary.

The next task is to relocate your rocks or aquarium decor to the RITZ.  This doesn’t have to be very decorative, just functional.  The purpose of relocating the aquarium decor is to keep all the friendly bacteria alive during the repair.  The RITZ doesn’t need to be beautiful, just functional for a couple of days.

Don’t forget to fill a glass with the aquarium floor material and relocate the glass with the floor material to the RITZ.  It’s not necessary to dump the contents onto the RITZ floor.  Just keep it wet and submerged in the RITZ.

Once the decor has moved it’s time to move the aquarium occupants and filter assembly.  Gently net and move each occupant.  Don’t take too much time to accomplish this task.  Best to just dip and net with purpose.  The less time it takes to net your occupants the less stressed they will be moving to the RITZ.  A large net is really a good idea during this phase of relocation.  A large net gives the aquarist a much better chance of capture in a shortened period of time.

With the decor and occupants moved to the RITZ, finish moving water from the aquarium to the RITZ.  Bring the RITZ water level up to a normal level.  There will be 33% water remaining in the leaking aquarium.  This water is to be discarded and the aquarium emptied of any remaining flooring material.

The decision can’t be pushed off any longer.  Will it be replace the tank, or repair the tank.

Factors to help make the decision:

A new tank has a dollar amount associated with it.  If you don’t want to fuss with cleaning and repairing your present aquarium, then decide on the dimensions and find a good deal on a new aquarium.

If you don’t want to fuss with finding a new aquarium, then break out the gloves and start scrubbing down the walls.  This is a good time to thoroughly clean the aquarium walls of their algae and rinse out any remaining dirt.  Be careful not to use a scotch pad or its’ equivalent on the glass or plexiglass surfaces.  These abrasive pads are strong enough to scratch glass and plexiglass.  Once clean of dirt and algae its time to let the aquarium dry.

A dry aquarium is much safer to work on with a razor blade.  Any water acts like a lubricant and can cause you to lose your grip on the razor blade and possibly cut yourself.

If the glass was cracked it would be necessary to crumble the glass in place and remove the edges from each side of the  aquarium frame.  Fortunately we are only repairing a leak and that only involves removing and replacing the surface caulk.

To begin the process have a box of single sided razor blades to pull from.  To remove the existing silicone, angle the single sided razor blade at roughly a 75 degree angle.  The razor blade needs to be slid under the silicone calk slowly.  This may take several slices of the blade under the caulk to fully detach it from the glass.  There will be residual pieces still attached to the glass.  Take the razor blade and continue the process on each joint all around the inner surfaces of the aquarium.

It is important that all the surface caulk be removed.  There can be no pieces left on the glass or plexiglass.  To insure that all the old caulk is removed from glass, use acetone and a few clean rags.

Using acetone will insure the glass surface is clean and ready to be recaulked. Keep in mind that acetone is a volatile organic compound (VOC), which means it evaporates quickly and completely at room temperature. As it evaporates, it transitions from a liquid to a vapor state, and in the process, it tends to leave very little residue behind.

Acetone is commonly used as a solvent because of its ability to dissolve a wide range of substances and its rapid evaporation rate. This property makes it effective for cleaning, degreasing, and removing various materials. However, it’s important to note that while acetone itself doesn’t typically leave residue, the substances it dissolves might. As the glass surface is cleaned, the dissolved materials may be present in the acetone solution, so using a clean cloth or changing the cleaning solution can help avoid transferring residues back onto the surface.

Always exercise caution when using acetone and follow proper safety guidelines, including working in a well-ventilated area, wearing appropriate protective equipment, and avoiding contact with skin and eyes.

If the glass was cracked it would be necessary to crumble the glass in place and remove the edges from each side of the  aquarium frame.  Fortunately we are only repairing a leak and that only involves removing and replacing the surface caulk.

To begin the process have a box of single sided razor blades to pull from.  To remove the existing silicone, angle the single sided razor blade at roughly a 75 degree angle.  The razor blade needs to be slid under the silicone calk slowly.  This may take several slices of the blade under the caulk to fully detach it from the glass.  There will be residual pieces still attached to the glass.  Take the razor blade and continue the process on each joint all around the inner surfaces of the aquarium.

It is important that all the surface caulk be removed.  There can be no pieces left on the glass or plexiglass.  To insure that all the old caulk is removed from glass, use acetone and a few clean rags.

Using acetone will insure the glass surface is clean and ready to be recaulked. Keep in mind that acetone is a volatile organic compound (VOC), which means it evaporates quickly and completely at room temperature. As it evaporates, it transitions from a liquid to a vapor state, and in the process, it tends to leave very little residue behind.

Acetone is commonly used as a solvent because of its ability to dissolve a wide range of substances and its rapid evaporation rate. This property makes it effective for cleaning, degreasing, and removing various materials. However, it’s important to note that while acetone itself doesn’t typically leave residue, the substances it dissolves might. As the glass surface is cleaned, the dissolved materials may be present in the acetone solution, so using a clean cloth or changing the cleaning solution can help avoid transferring residues back onto the surface.

Always exercise caution when using acetone and follow proper safety guidelines, including working in a well-ventilated area, wearing appropriate protective equipment, and avoiding contact with skin and eyes.

The sealant/caulk that should be used is one that will set clear, and is temperature stabilized.  It is not necessary to have an anti fungal agent in the sealant.  A good clear silicone sealant rated for outdoor use should work just fine.  Many aquarists use ASI Aquarium Sealant.

There is a two step process to applying sealant.  The first step is to evenly apply the caulk to each joint on the inside face of the aquarium glass.  The second step is to then use your finger to evenly spread the sealant in the joint.  Do not apply too much sealant so that it makes lumps when it is smoothed out with your finger.

The result should have equal amounts of caulk on each glass edge with a slightly smooth transition between the edge surfaces.  You want enough material to adequately bond with the glass surface making a good seal.

This step requires you to move with purpose before the caulk forms a skin.  Be certain to have slightly more at the bottom edge of the glass where it meets the bottom of the aquarium glass.  Once each edge is sealed leave it alone and let it skin over and set.  This may take 24-36  hours.

Create a test area by using some caulk from your finger and making a few swings roughly equal in depth to the caulk just applied, on the glass of the aquarium.  Use these to test for when the caulk has fully set.  They can be removed with a razor blade and a little acetone.

The first time repairing a leak may involve a mistake or two.  Not a problem, just wait for the caulk to set and then remove it to start over.

The aquarium has no limit to the number of times it can be re-caulked.  So, try, and try again…if you feel so inclined.

Before moving from the RITZ back to the aquarium, fill the newly sealed aquarium with water and let it sit overnight.  Check for any damp spots or drips.  If all is okay it’s time to set a moving day.

Relocating back home is a matter of reversing the process to move out.  The difference here is that you will need to replace the floor material that was removed earlier.  It is perfectly reasonable to have rinsed the material from the leaking tank and then put it back into the repaired tank.  After all it’s not like it wears out…

Remember to move 33% of the RITZ water to the repaired tank and then add 33% new water.  Check your water chemistry and adjust if necessary.  Relocate your aquarium decor in a manner to your liking and when complete the move the occupants from the RITZ to the repaired tank.

The last step is to pour out the floor material you had in a jar out on the surface of the repaired aquarium floor.  This will re-populate the friendly bacteria in the material back into the floor of the repaired aquarium.  Next move the filter and enough water from the RITZ to bring the repaired tank water level to normal.

That’s it.  Your fish and other creatures are back home.  Be sure to check the water chemistry.  There shouldn’t be any major changes other than what would be expected in a water exchange.

Even though you did a great job repairing the seals of the aquarium…be sure to check for leaks for the next few days…. just say’n.