Inlet solutions

This article shows you how to make different inlets if you´re planning to use the background as a biological filter, or if you want to place an inner filter behind the background. And that’s what we want, isn’t it? The water must then be transported from the front of the background to the back. There are many solutions to do this, and we will cover two of the most common solutions in this article.

  • Grill as an inlet (on some Back to Nature backgrounds, these are already installed)
  • Filter foam masked with peat or gravel

Installing a Grill

Back to Nature provides simple inlet grills. These have a diameter of 60 mm. Normally, one water inlet in this size will suffice for a small circulation pump. If you have an aquarium equipped with more powerful pumps – make more water inlets in the background. Expect one grill for a pump that pumps 400 liters an hour.

Drill a hole

Installing a grill is quite easy. Decide on where to place your water inlet. Hold the grill over the background and imagine where it should be placed. Drill the hole through the background.

You can buy this type of drill rather inexpensively at a D.I.Y-store. The diameter is 60 mm. You may also just drill a smaller hole first, and then cut out a larger hole using a knife.

Insert the grill

Blow away the chips from when you drilled the hole and place the grill in the hole. That´s it. Remember to take the strength of the pump into consideration, if the pump strength exceeds 400 liters an hour – make another inlet.


Filter sponge as inlet

One advantage of using filter sponge as an inlet is that you can determine the size of the hole to your needs, another is that it works a little as a pre-filter It is preferable to make two filter foams as you can simply change to the other when it´s time to clean the first one, and no curious fishes can swim into the open hole while you’re in the bathroom washing the sponge. In this article we will camouflage one with peat and another with gravel to show different options.

Carve out a hole

Begin by marking out where and how you want to the inlet with a felt pen. Then carve out the hole for the water intake as you want it with a knife. If you find the carving too. There is no right or wrong, shape the hole as you want it. In this example we made a rhomb-shaped hole, as we thought it matches the structure of the background a bit.

Shape the filter sponge

Cut off two pieces of coarse filter sponge ( about 5 cm thick). Shape them as the hole for the water inlet, but make them slightly larger. Make sure they fit in the hole.

Smear with silicone

Now that you have two pieces of pre-cut filter sponges, it´s time to camouflage them to make them less visible against the background. Pour gravel or peat in a small bucket. Squeeze aquarium silicone on to a bit of cardboard and press the front side of the sponge several times firmly into the silicone. Try to estimate that there is enough silicone on/in the foam for the peat or gravel to fasten, but not too much so the water can´t flow through it.


Peat or gravel?

Press the side that is smeared in silicone firmly into the peat or gravel. The use of peat or gravel or whatever is just an aesthetic thing. Any material suitable in an aquarium will work equally well.


The finished filter sponges, covered with peat to the left, and gravel to the right.


Wait approximately 12 − 24 hours until the silicone has cured, then wash the sponges in water. Now you can insert your custom made filter sponge into the water inlet.