What to Do When a Fish Tank Water is Not Level?

The water level of the fish tank can be unleveled due to two main reasons. Mainly, it happens when the fish tank is not levelled with the floor. Another reason is when the fish tank is not flush with the stand.

If the water level is not level, water might leak from the top of the fish tank and may fracture. Uneven pressure on the glass on either side causes the crack to form.

I’ll tell you about the prevention of the fish tank not level issue in this article. I’ll also talk about preventative strategies. To get the answers to your questions, keep on reading.

How to Level the Fish Tank with the Floor?

If the floor that the fish tank is standing on is not flat, the water will not be levelled. Follow this procedure to level the fish tank according to the floor:

  1. First of all, you have to inspect the level of the floor. You will need a spirit level for this procedure.
  2. Now, place the level on the floor and inspect the bubble inside. Now, if the bubble is tilting to one side from the middle even a little bit, the floor is not levelled with the earth.
  3. After that, you will need some wooden or metal shims. Put a shim on the bottom of the spirit level on the side the bubble is tilted. Change the position of the shim or add more shims until the bubble is right in the middle.
  4. Now, lift the aquarium stand using a bar and put a pump wedge underneath the stand. Inflate the pump wedge until you can put the shims underneath the corner of the stand.
  5. Put the spirit level on top of the fish tank and inspect the bubble. Adjust the shims underneath the stand accordingly by adding more. You might need to slide the shims a little bit towards the middle to level it properly.
  6. You have to level the other edge adjacent to the one you have just adjusted. Do it following the same process.

You might need 10 to 20 shims depending on the tilt. You should also make sure that the stand or the fish tank is not wobbly. You can watch this video on YouTube for a visual demonstration.

What to Do When a Fish Tank Not Level With the Stand?

If the problem is not with the floor, but with the stand, you have to make the stand levelled with the floor. You have to trim the edges that are higher to level it properly.

Follow this temporary procedure to level the tank with the stand:

  • First and foremost, put your spirit level on top of the stand. Inspect the bubble and notice which way the tank is tilting. Now, you need padded mats that you should put underneath the fish tank.
  • According to the spirit level’s reading put the mats underneath the tank carefully by lifting the tank.
  • Adjust the mats accordingly and inspect the spirit level by putting them on top of the fish tank.
  • You should also do this procedure with the smaller side of the fish tank to ensure that the water is levelled in both dimensions.

You can also put Styrofoam or polystyrene products underneath the aquarium stand to adjust the water level.

Is It Safe to Put Foreign Objects Underneath the Fish Tank?

Although you can put something underneath the fish tank to adjust the water level with the floor, it is not safe to do so. You can temporarily do it until you fix the unleveled stand.

If you put hard objects like metal shims underneath a glass tank, there is a high possibility of developing cracks in the glass. This is called a pressure crack which is built from uneven pressure on every area of the base.

The cracks can progress over time and as a result, water may leak from the cracks. The fish tank can also shatter if there are too many cracks.

So, it is always better not to put anything under the fish tank other than soft padded mats or Styrofoam. To adjust the level, always put shims between the floor and the stand.

How to Fix a Cracked Fish Tank Due to Being Not Leveled?

If the crack in the glass of the fish tank is still undeveloped, you can fix it. Follow this step-by-step guide to seal the crack:

  1. You have to move the fish to a safe temporary area such as an empty fish tank, or buckets.
  2. Now, remove everything from the inside of the tank. You should take out the water filters, water heaters, various decorations, grass, pebbles, and all other objects from the fish tank.
  3. After that, you have to buy some silicone gel that is safe for use in aquariums. Most silicone gels are not safe for fish since they are toxic. So, be careful when buying one.
  4. If the crack is on the base of the fish tank, position it properly. Then, put a piece of glass that has been cut accordingly to the size of the crack.
  5. Now, add silicone to the smaller piece of glass and install it on the cracked spot.
  6. If the crack is on one of the edges of the fish tank, add some silicone gel directly to the crack. Then, apply it equally using flat cardboard or metal.
  7. Wait for an hour to make sure the silicone has dried. Now put everything back inside the fish tank after cleaning it.

It is always better to fix the crack as soon as it develops. If you delay, the fish tank can leak water damaging the stand and the floor.

Which Tools Do You Need to Level the Fish Tank?

You need to use some products for the prevention of the fish tank not level issue. You also need some tools for fixing any cracks. Take a look at my suggestions:

  1. Work Pro 3-Piece Spirit Level Set
    – Includes three different sizes (9”, 16”, and 24”) for precise inspection.
    – High visibility green bubbles with 3 vials.
  2. Precision Brand Carbon Steel Shim Assortment
    – 6 inches wide with a thickness of 0.001”, 0.002”, 0.003”, or 0.005”.
    – Made of carbon steel which can be used for leveling platforms.
  3. Aqueon Aquarium Silicone Sealant
    – Non-toxic product for use in fish tanks and aquariums.
    – Easy to apply, colorless, and flexible.
  4. Calculated Industries Inflatable Pry Bar Alignment Pump Wedge
    – Inflatable air wedges for raising and leveling objects.
    – Up to 3-inches gap with a 500-pound lifting capacity.
  5. Amazon Basics Rubber Furniture Pads– 4.3 x 4.3 x 1 inches dimension
    – Slight elevation is provided by a strong rubber structure.


The glass in the fish tank might break if it is not levelled. You should check its level once a month since the wooden floor or stand is prone to changing shape gradually. Remove any sharp things from beneath the fish tank as well.

To avoid cracks follow the directions I have provided. You should also follow the prevention techniques of the fish tank not level issue in this article.

You can also buy the products needed for the procedures according to my suggestion.

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Arif H Fahim

Welcome to PetFishTank! My name is Arif. I make an effort to publish educational articles using my many years of expertise as a fish owner.

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