How to make your own background modules in Styrofoam

How to make your own background modules in Styrofoam

by Mikael Nilsson

This article will show you an easy and cost-efficient way of creating your own background modules for your aquarium. The technique described here can be used to make larger backgrounds covering your entire aquarium as well as a single module. How you choose to work is up to you. As usual, it is only your imagination that sets the limits.

My experience is that a larger background in one piece is harder to create, needs to be created more precision since it has to fit well over a large area, and finally it takes a whole lot more work to get it in the aquarium. That is why I chose to work with smaller modules instead.

Materials and tools needed
Styrofoam
A sharp and preferably thin knife
Dry colour pigment
Concrete mix
Paintbrushes
Silicone sealant

Optional
Hot air gun or blow dryer

Time needed - 2 or 3 afternoons should do

Difficulty - Easy

Styrofoam cutting

The first thing to do is to plan your work. How do you want your modules to look? What colour, what kind of stone should they imitate, how would you like to place them in your aquarium etc? You can of course just as well just go ahead and be creative, but if you plan to e.g. hide a heater or a filter system behind your background, it could be wise to plan it from the beginning.

Start with separating a piece of styrofoam that has the right size. Now all you have to do is carve your way to the shapes you like. I found that a very sharp and thin knife is easier to use than a thicker knife.

From uncut styrofoam to final shape

In order not to get a too smooth surface it is good to bend loose styrofoam pieces as much as it is possible. If you only cut your way through the material you will end up with unnaturally smooth surfaces and sharp corners. Instead, cut down a bit in the styrofoam as in the middle picture above, and then bend the knife to the side until a small part breaks loose. This way you end up with rough asymmetric surfaces, which in my opinion, looks more natural.

Depending on what kind of look and feel you want on your modules, you can use a hot air gun to melt the upper layer of the styrofoam. The fumes are very poisonous so do this in well-ventilated area. A module, which has been melted, doesn’t mess any more, and it has smoother surface. If you skip this stage, you will end up with a module, which has a bit of a “lava look” over it.

Result with non heated styrofoam

Result with heated styrofoam

Concrete coating

Once you have a styrofoam piece that you are pleased with, it is time to use the concrete. Mix your concrete according to the instructions on the packet. Depending of how much water you add, your concrete will become more or less viscous. I prefer a thicker mix, which is more forgiving in covering up small mistakes or other parts that look too much like styrofoam.

When the concrete is mixed, add dry colour pigments till you have the colour of your choice. You should consider that the concrete will change its colour when it’s drying and you will end up with a much “whiter” colour than the colour you had on your concrete mix.

The colour looks alot darker when wet

Let the module dry thoroughly and then paint it with at least two more concrete layers. The more layers you get, the better the module will withstand scratches and wear. When all layers are there and everything is dry, all that is left is to assemble your modules in your aquarium and fix them with the silicone sealant. I find this the trickiest part, but hopefully you’ll find a combination that your pleased with without to much effort.

I’ve only just a single colour on my modules, which in the combination of light and shadow in the aquarium looks pretty natural. I have also seen beautiful examples of people who paint their backgrounds in several colours creating an even better look. It all depends on how much of an artist you are.

Finished result with fascinated demasoni and golden fry.

In the picture above I’ve used a black plastic film on the outside of the aquarium. I’ve also made two modules that the fish can swim behind. This turned out to look very good, but it makes catching fish a whole lot more difficult!

Concrete increases your pH and kH, which often is good for Malawi and Tanganyika, but not always appreciated by other fishes. If needed it is always possible to put a last layer of varnish. This will also protect your background from taking damage from fish like Ancistrus etc.