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    3D Rocky Background


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In a previous article, building the polyurethane foam 3D background has been described. As stated there, I made other backgrounds using the PU foam but it served only to glue the rocks to an aquarium glass. Any rocks which don’t change the chemical properties of water are fine for building the background. They are for example limestone, tufa, lava rocks, slate, granite, marl etc. I had used the limestone, marl, slate, and granite.

Limestone background

I built the background from the limestone full of holes in a 190 litre tank, where the Malawi cichlids were kept. I decided to use the real stones because fishes tried to nibble algae from the PU background but it was difficult for them to do it as the background was siliconed and sanded. I tried to realize a job that was a hard nut to crack, to cut the rocks as slim as possible. It is clear that only pieces with one original side were useable, it means that the middle part of the rock was a scrap. I tried to cut about 2 – 3 cm thick slices. It wasn’t always possible because to hold the rock by one hand on the ground and cut it by the second hand was not easy at all. I used an angle grinder with the stone grinding disc. Ten disc were wearied and I nearly sawed my fingers :-)

Warning! Use the dust mask or any kind of dust filter while cutting the stones. The best solution is to cut it outside. I did it in the garage and very fine dust was everywhere. Use the leather work glove as the risk of injury is high. Protect your eyes with a safety goggles or face shield. Don’t underestimate the risk of injury!

Pic. 1 – The rock layout Pic. 2 – The rock layout Cut, washed and degreased rocks were then laid out on the area that had the same dimensions like the back glass of the tank where the background had to be done. It helped me to prepare the rock layout in order they fitted together and to realise how many rocks I need. The situation often changes during the gluing the rocks but it is a good idea to prepare an approximate layout at least (Pic. 1 and Pic. 2). After the back glass was clean, the foam could be sprayed.

The work should continue gradually and you should spray only the thin layer of foam because it expands and lifts the rocks up. The rocks are then sliding on the foam like on ice. More foam than needed also covers the rock edges and the situation is blind. The rocks should be pressed together and to the glass during the foam cure.

If you want to hide the technics (heater, filter, sucking pipe etc.) we will need to make a stack or socket in the corner. In this case, I glued the polystyrene stripe into the left corner of the tank (it can be seen out of the tank - Pic. 1). It created the triangle socket in the corner. The L-shaped stack can be made sure. The polystyrene stripe was glued by the PU foam. The excessive foam was cut off after the cure. An opening was cut in the polystyrene stripe near the bottom through which water flows to the sucking pipe of an external canister filter. Then I glued the rocks also on the polystyrene stripe in the corner and the background was ready rough. The long-term work at the background finishing had continued. As the foam has expanded during the cure from the crevices between the rocks, it was needed to remove it. I used the scalpel and tweezers. It is essential to clean every rock completely, otherwise the foam remains would be seen in the water. The foam should be ripped and removed by tweezers first, or by hand and scraped from the rocks by knife or scalpel. Clean rocks look much better. Now, the crevices in which the foam left between the rocks need to be disguised. It is not needed to remove the foam from the crevices completely.

The crevices were filled with the silicone and sanded with the sand coloured properly to match the rocks colour. The silicone was left to cure for 24 hours and all the procedure was repeated. After the silicone had been cured, the background was rinsed by water. Then the aquarium could be filled. After some time, algae covered the background and fishes are happy to graze it all the year.

Pic. 3 – A few glued rocks Pic. 4 – A view at the almost complete background ic. 5 – Detail view from above Pic. 6 – Front view

Pic. 3 - The rocks are glued close together and the extensive foam is removed after it cures. The picture shows the blue-green foam on the left. Don’t use it as it colourizes water to blue-greenish colour.
Pic. 4 - All the rocks are glued. It is needed to remove the extensive foam and joint the crevices with the silicone and sand.
Pic. 5 - Detail view at the left corner of the tank with prepared polystyrene stripe which will be covered with the rocks. The space behind it will serve for placing the heater and sucking pipe of an external filter.
Pic. 6 - General view at the almost complete background with partially cleaned crevices on the right.

Obr. 7 – napustené akva Obr. 8 – akvárium po mesiaci Obr. 9 – akvárium po roku

Pic. 7 - The complete background after the filing the tank. Internal filter is placed in the tank temporary to remove the turbidity.
Pic. 8 - The background in the tank after 2 months.
Pic. 9 - The background partially covered by algae after the year.

Marl background

PThe background for the 419 litre tank was done similarly like described above one. The only difference is that I used the marl rocks which are light cream-coloured. The aim was to build the as light background as possible because I wanted to keep the black species of Tropheus in this tank and they look best with the light background. Formerly, I thought to cut the white limestone. It is much harder than that used in the previous plan. I found the marl rocks which are very suitable for making the background. They are light and cleavable. No cutting. I brought a few tenths kilogram of these rocks home and cleaved as thin as possible. This background should not look like the one described above but should be flat, not take much space and imitate the rock pile. The preparation didn’t take too much time as there was no need to cut the rocks. The rocks were cleaved easily. The only thing I had to do was to clean the rocks from the dirt. I also put them into SAVO solution (a chlorine-based cleaner and disinfectant).

Ďalší postup bol už rovnaký, ako pri predchádzajúcom pozadí. Odmastiť kamene a sklo, predbežne si uložiť kamene, ako budú umiestnené v akváriu a postupne lepiť. Ako v predchádzajúcom prípade, aj tu som použil PU penu. Po nalepení všetkých kameňov som pomocou pinzety a skalpela odstránil prebytočnú penu zo škár medzi kameňmi a očistil okraje kameňov od peny. Potom som pomocou transparentného silikónu vyšpároval škáry a vysypal pieskom. Nechal som pozadie 2 dni vyschnúť a povysával od neprilepeného piesku.

Similarly, like in previous plan, I made the stack in the left corner hiding the pipe which drains the water to the sump under the tank. In this case it is a DIY filter. The pipe leaves the tank through the back wall hole. All is hidden behind the background. More show the pictures below.

Pic. 1 – Rock layout Pic. 2 – Detail picture Pic. 3 – Glued rocks

Pic. 1 – Rock layout and a few rocks glued in the right down corner. On the right side of the picture, there the pipe connected with the bulkhead can be seen.
Pic. 2 – Detail. The cured foam between the rocks are then removed. The excessive dry foam should be removed when gluing the next rocks.
Pic. 3 – Glued rocks and removed foam from the crevices between the rocks.

Pic. 4 – 3D rocky background Pic. 5 – 3D background – stack
Pic. 4 – General view at the complete background.
Pic. 5 – Upper part of the stack is removable to allow to get to the pipe and bulkhead in case of dismounting.

Pic. 6 – Side view a few days after the tank filling.
Pic. 7 – General view 7 months after the filling.
Pic. 8 – Detail view at the background 7 months after the filling.

Pic. 6 – After filing with water Pic. 7 – General view Pic. 8 – Detail view

Slate and granite rocks background

The building the background from the slate is similar to the previous ones again. The advantage when using the slate is that it is easy cleavable to thin slices. It lowers the weight of the background. The slate can be interlaced easily so there is no need to joint the crevices. Except of slate, I used also the granite rocks that are dark like the slate. I wanted the slate continued with granite rocks at the bottom. The background looks much natural.

After planning the layout, the slate was glued to the back glass of the tank with PU foam. The individual slices were glued to interlace each other. In the bottom third, the granite rocks were glued. After the foam had cured, the extensive foam was removed and the deeper crevices were jointed with silicone and filled with small parts of slate if needed. It is not suitable to use the sand to joint the crevices due to the different colour of the slate and sand. As mentioned above, there is no need to joint the crevices but I planned to keep small fishes (tetras) in this tank so it was safer to do it.

Even the tank is dedicated for the small fishes where the rock background is rather unusual, it is a nice addition to the aquatic plants.

Pic. 1 – Background from the slate and granite rocks Pic. 2 – Background from the slate and granite rocks Pic. 3 – Background from the slate and granite rocks
Pic. 1, 2 – General view at the complete background with jointed crevices between the rocks. Granite at the bottom, slate above.
Pic. 3 – Detail view at the complete background.

Pic. 4 – 2 months after the filling with water Pic. 5 – 2.5 months after the filling with water Pic. 6 – 3 months after the filling with water
Pic. 4 – An aquarium 2 months after filling with water.
Pic. 5 - An aquarium 2.5 months after filling with water. The background is a nice addition to the plants and the fishes feel safer.
Pic. 6 - An aquarium 3 months after filling with water.

FAQ - Read the frequently asked questions about "3D Background".

DISCLAIMER: By building this DIY project you agree not to hold the author responsible for any injury or bodily harm you may cause to yourself or others. Read all safety instructions pertaining to equipment prior to use.

Copyright © 2003 - 2017 Robert Toman




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