What To Put Under A Fish Tank [6 Options]

If you’ve landed on this page it means that you’re wondering what you can put under a fish tank to avoid furniture damage, tank cracks, or other unpleasant surprises. That’s exactly what we’re going to talk about today. Let’s dive right into it.

Things You Need To Know

  • Aquariums need to stand only on FLAT SURFACES. If  the base is not completely flat it will lead to tank cracks.
  • Aquariums with plastic trim provide more support in holding the tank weight.
  • Framed Aquariums have the weight distributed evenly across the frame.
  • Glass Aquariums need cushioning and support around the outer edges.
  • Aquariums are much heavier than you imagine. The place of the aquarium should be solid and stable enough to hold the weight of the aquarium.
  • Aquariums accumulate an incredible amount of weight once they’re filled with substrate, rocks, wood and water. Even the smallest imperfection of the surface creates a pressure point on the bottom of the glass and will eventually make it crash.
  • The surface must be flat and free of vibration.
  • Use wooden shims to level the stand in case of an tank edge not touching the surface.
  • Foam needs to be cut and added along the tank perimeter only [on the edges of the frame]. The center of the aquarium will be kept open because it avoids the foam pushing up on the bottom glass.
  • Do not use foam under aquariums with a plastic trim. Foam compresses enough to reach up the bottom glass and cause seal failure.
  • Rimless Fish Tanks [with flat bottoms] to be leveled with a thick and compressible material [rubber, polystyrene, yoga mats]. The tank weight will be distributed on the whole bottom.
  • It is important to acquire a good quality aquarium from a reliable manufacturer. It will avoid potential quality problems.
  • Some manufacturers recommend not putting foam underneath the tank. Check first with your tank manufacturer in order avoid having the warranty invalidated.
  • Fish Tanks need to be resealed every 10 years.

What To Put Under A Fish Tank

Every tank needs to have good support underneath. It prevents tank failure, tank leakage and tank crashes. Unfortunately, tank failure is very common; especially large tanks fail and crack in time due to uneven pressure and uneven surfaces.

Tank cracks and crashes occur just because most of the tank stands, floors or other surfaces are uneven. Here’s what options you have in terms of what to put under a fish tank:

1. Aquarium Mats

Aquarium Mats are the best option for large, medium and small fish tanks. They are made out of a rubber base and dense foam resistant to damage. They serve as a protective lining under the aquarium and protect perfectly the aquarium’s delicate glass bottom from damage.

At the same time, they protect the surface of the furniture from scratches through the glass bottom of the aquarium [can also be used for this purpose under terrariums].

Aquarium mats provide thermal protection by limiting heat leakage from the tank and reducing the electricity consumption for heating.

They are super easy to use and can be directly applied on the surface. The protective pads usually come in dark colors, which make them almost invisible when placed under the tank.

However, many hobbyists prefer using other materials for aquarium cushioning purposes as these materials are found in different sizes, dimensions and variety on the market. It really depends on each person’s needs and preferences.

2. Rubber Sheet

Thick Rubber Sheets are efficient in preventing surface imperfections and irregularities. Rubber is a great leveling option for stands, tables and uneven floor surfaces.

Placing a rubber sheet under a tank or terrarium enhances stability and support. It helps smooth out bumps, provides insulation and holds the tank weight securely in place.

Rubber prevents slips and doesn’t allow moisture to reach wooden furniture.

3. Expended Polystyrene [EPS]

Using EPS Sheets is another way to make up for possible unevenness of the surface. The polystyrene protects the bottom of the aquarium from defects and imperfections of the contact surface.

A polystyrene plate placed between stand and aquarium avoids punctual loads, eliminating possible weak points created by uneven tank pressure.

Recommended thickness: 2cm – 5cm

4. Plywood Sheet

A Plywood Sheet will make a great base for your stands. Plywood is solid and provides excellent support for rimless tanks [glass or acrylic]. Adding then a thin layer of foam will level any slight imperfections in the plywood surface.

5. Oriented Strand Board [OSB]

An OSB Sheet is another suitable option for cushioning between aquarium and stand. Oriented Strand Board (OSB) is an alternative to plywood; it is affordable and makes an ideal support panel for stands. They’re also appropriate for use in humid conditions.

Recommended thickness: 3/4”

6. Foam Sheet

Foam Sheet is used to protect rimless tanks. Placed under the bottom of the aquarium on the stand, it prevents the glass to strain. The foam will compensate for any flaws in the stand or floor.

Bumps and imperfections are likely to exist on the surface of the aquarium holder. The foam absorbs any of the high points and helps smooth out the bumps that may hide below your aquarium.

Foam helps distribute the aquarium weight around the perimeter of the aquarium. It keeps the fish tank leveled and has a high compressibility.

Heavier tanks need denser foam because they have to support larger weight and compression power.

Recommendation: Place the foam on OSB / EPS Polystyrene sheets

Stryrofoam absorbs irregularities and imperfections that might exist in your stand. A Styrofoam placed under the tank provides cushioning and minimizes any stress put on the bottom glass of a rimless tank.

Make sure to use Styrofoam on a flat, leveled surface or stand. Styrofoam does help to level and it does not make up for any bows on the surface.


Many surfaces that often seem flat and straight are not.

Setting up correctly a solid, flat base and structure for your aquarium helps prevent any future accidents of the fish tank.

Take into consideration your aquarium size and capacity, the manufacturer’s indications and the tank placement.

It takes only a few strands of sand between the aquarium glass and the surface to crack and ruin a fish tank. That is why Pads and Sheets act as excellent buffers and absorb any imperfections.

Remember to reseal the silicone every 10 years and make the most of your dream aquarium by enjoying it every moment.

Sorin Trifu

Hi & Welcome to My Blog! My name is Sorin and I'm 26 years old. I've always been a Pet LOVER and I've always enjoyed writing. I had my FIRST Pet when I was 6 years old and ever since then, I've learned a lot about Pets. I'm glad to combine my passion for PETS & WRITING and share with you ALL my knowledge about them.

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