How to build a background offibreglass plastic
I had for a long time been wondering about a new background to the largest of my aquariums. Earlier I have tried backgrounds made of Styrofoam, without being completely satisfied, since it's hard to reproduce the style of nature. The backgrounds called Back-to-Nature are today the closest to the reality I believe. Then I found the solution for my thoughts! - An article in Ciklidbladet 6/98 (Swedish magazine for the Nordic Cichlid Association) described how to create a casting of a rock in fibreglass plastic.
Since we have several rocks along the coast of Kullabygden (in the southernmost part of Sweden), I just had to start looking for an appropriate rock to make the casting. The most difficult part seemed to be how to find a rock by the measures of 160x60 cm, smooth enough to fit into my aquarium.
When I finally found the appropriate rock it was time to start looking for material to build the background. A local shipyard appeared to be the cheapest one on fibreglass. Wax, gel coat and polyester were bought on Biltema (Swedish company selling car-accessories) to a reasonable price.
To test the method I tried to make casts of a couple of roofing tiles. My attempt went well, so the next day I went back to my selected rock. When I arrived, I started to clean the rock with a steel brush. To be assured that the casting would loose easily I waxed the rock two times with car wax. Now it was time for the most important moment - the gel coat! The gel coat will become the surface of the finished background. It's important, during applying, to make sure that the gel coat covers completely. Perhaps it's wise to apply two layers of gel coat?
While the gel coat hardened, it was time for me to take a coffee break and to prepare for the next phase of the work. Approximately 3½ hour later I returned to find out that I wasn't alone at my rock anymore, an older nude pair had decided to take a swim only a short distance from my casting (we all have our different kind of curious habits - some of us paints plastic on rocks!). I applied a rich layer of polyester before the first layer of fibreglass, it's important that the fibreglass get contact with the gel coat. To make it easier to loosen and transporting the background home, I decided to apply only two layers of rather thin fibreglass, to strengthen it later back home. Between the layers it's not necessary to apply as much of polyester. It's better to give the fibreglass the time to soften.
5 hours later I returned to pick up my casting. I began to detach the edges with a crowbar, piece by piece. When the whole casting finally was detached, I was really satisfied with the result. Small pieces of the gel coat had loosened, for that reason should some supplementary work become necessary. The background was loaded into the car and transported home. The next day I added two layers of thicker fibreglass on the backside to improve. Next moment was to fill up where the gel coat had loosened.
From the beginning I had made the background 15 cm too large, both on the height and the width, to be sure that it should fit into the aquarium. Before continuing with the painting, I roughly cut down the size of the casting. The last measurements and cuttings I did first after the painting. The background was already coloured white of the gel coat. To make it look more real, I bought some yellow and grey colour that I applied with a sponge. Because the background should imitate a chalkstone-rock, I let most of the surface stay white.
Now it was time to test the background into the aquarium to mark and to cut the last edges. The background suited perfectly, and all I had to do was to squeeze a bit to fit into the aquarium. Two holes were drilled to connect the external filter with plastic pipes.
Before varnishing, I put a line of silicon around the edges. After consulting the personnel in the chemist store, I decided to buy a dull 1-component boat varnish. I applied two layers of the varnish, and to the second layer I added barely a bag of slippery protection powder to give the algae a better chance to attach to the surface.
On the bottom of the tank I put a 10 mm board of Styrofoam, to protect from stones breaking the bottom, which could easily happen when keeping digging cichlids. The background was placed on the Styrofoam, sand and stones added and water was finally filled into the tank. After some days with filtration, I added a couple of "test fishes" to see if the water was free from toxically substances. The "test fishes" seemed to be all right and after another two weeks I let all my fishes into the tank.
When this is written the aquarium has been up and running for a month and the algae has attached to the background, just as planned. My Metriaclima Estherae and Ps. "msobo" eats the algae that have grown onto the background. Except for the nice outlook of having a background in the aquarium, it is very practical not having to clean the backside glass.