« back to FAQ | Home »
FAQ - 3D Backgrounds

May I glue the rocks to the styrene board using the polyurethane foam? Is it a good idea considering the strength of whole background construction?
It is possible to glue the rocks to the styrene board. PU foam will hold them. Personally, I don't recommend this approach. The styrene board 1-2 cm thick (and I think even thicker) is not able to hold all the rock weight. I'm not able to imagine how to move this background into aquarium. The styrene board will break. It had to be glued to the aquarium back wall first and then the rocks could be glued but then rocks can be glued directly to the glass with PU foam. If you will make the backround using the PU foam to glue the rocks to the glass, it is not forever. PU foam can be removed from the glass much easier then the silicone.

How to defat the aquarium glass and rocks before they will be glued? Is it some detergent useful or something stronger (petrol, diluent)?
I don't recommend to use any detergent. It is hard to wash and can be then dangerous for fishes. I use to use a common denatured alcohol. Also alcohol for spirit-lamp is suitable. It defats everything safely.

What is the long-term experience with the background made of marl? Was it really so easy to work with it?

Experience is good, no negative things to mention. The background is covered by algae so it isn't that bright like at the beginning. It was really easy to handle with a marle stones, it is similar like dark slate. It can be cleaved. Sometimes it was a little bit difficult but some pieces were thinner than 1 cm.

May I use any polyurethane foam for background building?
Basically yes but I don't recommend to use the special PU foams containing variuos additives, like foam desired for frosty conditions, colour foams (blue, green). They release the pigments itno the water. Common white or yellow PU foam is fine.

How to clean the rocks of moss and other dirt? File card/brush could be good but doesn't it scrape the rocks? May I use the chloramine solution?
The rocks are best submerged in hot water and wait until the dirt is wet and soft. Then clean them carefully of the dirt with hard bristle brush. Then the rocks can be put into the chloramine solution for a few days. I don't recommend to use the chloramine for darker rocks which may change their color to brighter. Use only with white or bright rocks. darker rocks can be submerged in the chloramine solution for a few minutes. After the chloramine bath, clean the rocks with the brush again or use any other tool to remove some small dirt, plant roots, moss etc. The rocks should be put into clean water for a few days (1 week) to wash residual chloramine. The water cean be changed during this period if possible. Anyway, 1 week bath in clean water is enough and I have never noted problems with fishes.

What kind of silicone may I use for polyurethane backgound coating? Must it be an aquarium silicone or any other kind?
It is essential to use only an aquarium silicone or other kind of silicone where is stated it can be used for aquarium building. Any other silicones often contains antifungal additives which are toxic for fishes. It is also often the cause of fish death. I saw it in my brother's aquarium. He used that silicone in the background building and after the tank cycling and putting the fish in, all except 2 (they were saved by removing into the clean aquarium) were dead. He had to remove all the background and make another one using a suitable silicone. It doesn't matter which brand of silicone is used. There are no need for silicone with a high adherence. I used Ceresit, Titan, Den Braven, Soudal and very good Dow Corning 881. It depends what is the purpose of silicone using. For the background, any cheap silicone is fine as isn't used for joining the parts but for the coating the PU foam. Quality silicones like mentioned Dow Corning 881 or Perenator are intended for glueing the bigger aquariums.

May I apply the polyurethane foam during the PU background building directly to the back wall of the aquarium? Will they stay under water after the tank is filled?
I assume it will stay at the place. Although PU foam isn't as adhesive as silicone but it holds fine. It is important to defat the glass carefully. Also you can spray a few flat rocks into the backround. They will help to hold the background under water.

How to spread transparent silicone the polyurethane foam or styrene background?
The silicone spreading principle is very simple, use your fingers :-) I tried various brushes and other tools but human hand is the best tool. It depends on the surface segmentation. If it is flat, some brush can be use for sure.

Copyright © 2003 - 2012 Robert Toman



Description of my aquariums, breeding history, photos and everything that happened in each tank during the time.


Tips and tricks for doing a various tools and equipment for fish keeping. Here, you will find an inspiration for your own attempts to simplify the fish keeping.


My own experience with African cichlids breeding. A detailed description of fish keeping and breeding with special things I found during the years of fish keeping.



My own photos anf videos of fish kept in my tanks.

Didn't you find your language? Write me, I will add it here!
Cichlidworld on FacebookCichlidworld on TwitterCichlidworld YouTube
Cichlidworld RSS
Search only Cichlidworld.eu