ᐅ Has anyone reinforced their KALLAX shelf to use it as a base for aquariums?

Hello everyone,

I am planning to place an aquarium on an IKEA KALLAX shelf. Since I know that KALLAX is not originally designed for such heavy loads, I wanted to ask if anyone here in the forum has experience reinforcing their KALLAX shelf to support an aquarium?

I am especially interested in specific reinforcement options, such as additional wooden panels, metal braces, or other sturdy inserts to minimize the risk of deformation or even breakage. Any information on load limits and tips for even weight distribution would also be very helpful.

Has anyone reinforced their KALLAX and can share how stable the shelf is afterwards? I am looking for a recommendation that is as practical and straightforward as possible.

Thanks in advance for your experiences and advice!

Hello mumimau,

I understand your concern well and can gladly share some basics and experiences. The KALLAX is generally designed for light to medium loads; the plastic and particleboard shelves are not particularly strong against point loads or sustained heavy weight. An aquarium, especially one containing a large volume of water, can quickly exceed the load capacity.

Many users increase the support area by placing sturdy OSB or plywood panels, which help distribute the weight more evenly. Metal components are rarely used since they can complicate the appearance and assembly.

Here are some points to consider:
- Panels should cover at least the entire shelf surface
- The unit must stand on a level and solid floor
- Reinforcements beneath the shelves help reduce stress

If the aquarium holds a very large volume of water, around 100 liters (26 gallons) or more, I recommend additionally stabilizing the base or side walls with cross braces made of wood.

How large is your aquarium, and do you already have any specific ideas on how to reinforce the shelf?

emmaju schrieb:
Many users increase the support area by placing sturdy OSB panels or plywood sheets

Thanks, that makes sense to me. My aquarium is about 80x40 cm (31x16 inches) with a height of 50 cm (20 inches), so roughly 160 liters (42 gallons) of water plus equipment and decoration. The weight is quite substantial, and I definitely don’t want to risk the shelf giving way.

emmaju schrieb:
The shelf must stand on an even and solid floor

That applies in my case; the floor is not tiled but a stable wooden floor with a concrete slab underneath.

One more question: Is it enough to place a wooden board only on the top shelf surface, or should the inside sides also be somehow reinforced to prevent sagging? I’ve read that shelves are generally not designed to hold that much weight.

Hello everyone,

I can completely relate to mumimau’s concern. I’ve been thinking about this myself, as I recently placed a small basin on a similar Kallax unit. I was really nervous about whether it would hold up or not.

mumimau schrieb:
Another question: Is it enough to just place a wooden board on the top shelf, or should the inside sides also be reinforced somehow?

In my experience, having continuous reinforcement under the shelf is very helpful. I installed a plywood board approximately 2 cm (¾ inch) thick that rests on the side panels of the shelving unit. This completely prevented any bending. I inserted felt pads between the shelf sides and the board to avoid any pressure marks.

Still, I always had a bit of unease, mainly because I imagine over time the strength of the particle board could decrease if it is constantly loaded like that.

Have you thought about whether the shelving unit should perhaps also be better secured overall with metal brackets, either glued or screwed? I think that could really add extra safety.

In short:

Use plywood or OSB as a base layer.
Install cross braces made of wood or metal.
Ensure a stable subfloor.
Avoid point loads.
Not only reinforce the top, but also stabilize the sides if there is a lot of weight.

This is sufficient in most cases.

Reidki schrieb:
Have you ever considered whether the shelf might be better glued or screwed together overall with metal brackets?

I think that’s a very good suggestion! Especially for shelves like KALLAX, which aren’t really designed for heavier loads, I would definitely recommend additional screws or brackets.

Personally, I have similar concerns with my tank and plan to reinforce my KALLAX soon with metal brackets inside the corners to significantly increase stability. One example would be to screw the shelves to the sides from underneath using brackets, which would make lateral warping more difficult.

Luchen schrieb:
Not just reinforcing at the top, but also stabilizing the sides

I agree completely. You should support both the surface where the aquarium stands and the sides of the shelving well.

I would also recommend thinking about additional support measures: for example, placing the aquarium feet on a sturdy board and then using that board to better distribute the load.