DIY 3D aquarium background.
If the back wall is decorated inside the aquarium, certain requirements must be met for the materials. I would like to note that with today’s abundance of dry mixes and pigments, it is best to use the simplest ones, namely natural pigments such as ochre, umber, and cement, without any plasticizers, retarders, or fillers. Trendy mixtures can be simply dangerous for fish. In principle, you can use only those materials that are used for all other parts of the tank, i.e., primarily stones and wood.
Usually, individual elements for decorating the back wall are glued together and then fixed to the glass of the aquarium from the inside. However, depending on the type of gluing, this can lead to uncontrolled accumulations of dirt after installation, so it is wiser and more hygienic to assemble the entire back wall as a single unit outside the tank and then glue it in (while dry).
Before starting work on making a 3D background, carefully read the instructions for using polyurethane foam and epoxy resin. Water from the aquarium itself penetrates into the pores of mounting foam. The organic compounds contained in it will sooner or later begin to decompose, which does not improve water quality at all. Often, manufactured structures are coated with various sealants or epoxy resin, but who can guarantee that holes or cracks will not appear in the coating and water will not seep through them?
This is done as follows: you need to take a dark gray rigid PVC plate and cut it precisely to the size of the back wall so that it reaches the top rim of the aquarium. It is wiser and more hygienic to assemble the entire back wall as a single unit outside the tank and then glue it in (dry). Then you can lay out and glue stone crafts (dry!) onto this plate using silicone rubber. You can even glue stones that will protrude forward in the aquarium itself (they should be placed vertically now). If decorative roots are supposed to “grow out of the wall,” you need to leave a place for them on the plate.
When everything is glued and the silicone has cured, polyurethane foam should be squeezed onto the free areas of the plate (where the gray color is visible, as well as other unoccupied places). This is the exact moment to take roots pre-soaked in water, press them into the foam, and hold them for a few minutes in the desired position. The foam compresses and holds the roots in the position they will later occupy in the aquarium, creating shelters for fish.
After a few hours, the foam hardens, and you can work with it further, armed with a small knife. The so-called grapefruit knife is great for this: it is slightly curved at the front, and has serrations on both sides of the blade. When everything is ready, the plate needs to be smeared around the entire perimeter and glued to the back wall. Silicone rubber is used for this again. All gluing points must be completely dry! If there is a little empty space on the sides, you can squeeze foam there later and trim it accordingly.
Aquarists know that keeping several cichlids together in a general aquarium requires shelters where fish can hide, weaker individuals can escape from aggressive ones, and sometimes spawning takes place. It is very important that shelters are located along the entire height of the aquarium from the bottom to the very surface of the water, which allows territories to be divided to some extent by “floors.” If the aquarium size is minimal, shelters should be located along the entire back wall at some distance from it (usually 5-8 cm), allowing fish to maneuver freely, moving from floor to floor. Usually, rock formations in the aquarium are built in the form of a back background or 2-3 separately rising rock masses, while leaving sufficient operational space for actively swimming fish.
For an aquarium with Malawi and Tanganyika cichlids, decorative reefs can be made from aerated concrete. It is light, easy to process, but has good buoyancy. To prevent your reefs from turning from underwater to surface structures, glue the aerated concrete structure using silicone sealant to stones or a plexiglass plate covered with a thick layer of substrate. You can also glue aerated concrete blocks to the back wall of the aquarium. The disadvantage of all these designs: it is impossible to catch a fish that has hidden in a secure shelter.
Making a 3D stone background. To make it, you will need: A piece of glass or plastic onto which stones will be glued. Aquarium silicone adhesive. Pieces of lava bought cheaply at a garden center. These stones are very porous and light (similar to expanded clay) and some even float in water. If you are going to use huge pieces of granite, you will have to think about how you will glue them. The work is simple: apply glue to the base and lay stones on it. You can glue caves and other decorations out of stones, which will be attached to the wall. After gluing the stones, they need time to dry, according to the silicone or resin manufacturing instructions. If you use epoxy resin, it is best to soak the resulting structure in water for a few days afterwards.
You can create a background using mounting foam. A one-liter can of mounting foam is enough to form a background with an area of up to 1.5-2.0 m at a thickness of 3-4 cm. A background made of such material will be quite buoyant; this fact must be taken into account, and overly bulky relief should be avoided. Spread a sheet of thick plastic wrap on the floor and moisten it slightly. Apply the foam and, using a spatula wrapped in plastic wrap, spread it evenly over the sheet. The foam expands in volume by about 2-3 times as it dries, remember this. If you are making caves, it is best to do this in several layers.
To make holes (for example, to hide a pump there later), take a cardboard tube from a roll of toilet paper and wrap it in plastic wrap. Or simply cut out the hole later. Pour substrate onto the wet layer of polyurethane foam; it will serve as a filler and weight down the structure. Re-apply a layer of foam on top of the substrate and spread it, shaping the surface relief. The foam will bind the substrate and turn into a homogeneous mass; flatten large and convex “bubbles” with a spatula. It is useful to embed small plant pots, stones, driftwood, and an air diffuser into it before full polymerization (1-2 days).
If necessary, create a mass with shelters for fish. You should get a slab of material resembling styrofoam, one and a half to two centimeters thick (depending on the speed at which you moved the canister). The slab is rigid and quite durable. Allow 1-2 days for full polymerization; when the foam is dry, separate it from the plastic wrap. Prepare a colorant from oil art paints and mix it with epoxy resin, then, using a brush and gloves, apply the composition to the entire surface of the background.
This needs to be done in several stages because epoxy resin thickens quickly. The 3D background must be thoroughly coated on all sides with a layer of epoxy resin. After that, insert it into the aquarium and glue it with silicone adhesive, do not skimp on the adhesive, otherwise it will simply tear away. Plant Java moss, Bolbitis, Thailand fern, Anubias.
The back internal background can be made of styrofoam. Take a sheet 1-2 cm thick, equal to the dimensions of the back wall. Decorative overlay details are cut out from other pieces, making through or blind holes (this is best done with a hot spoon). You can also use it to give the sheet texture. Apply them to the main sheet, fastening them with plastic pins or glue. The finished background is coated with waterproof paint; you can decorate it with pebbles, stones, and other decorations. It is dangerous to use dyes like printing ink to color the styrofoam surface — they are toxic. It is best to paint it with a synthetic epoxy-based paint, i.e., a two-component material.
To create a deep-relief background, it is better to use thick styrofoam (20 cm or more). Trim the styrofoam so that it matches the dimensions of the aquarium. You need to have a plan for the decorative wall in mind before cutting. After that, you can cut caves, stones, rocks, etc., into the styrofoam. All sharp edges of the styrofoam must be trimmed, otherwise it will look unnatural. A blade or a very thin knife can be used for trimming. After that, you will need to paint the walls with epoxy resin. Do not use regular paint because it can be poisonous to fish and plants. Epoxy paint must dry for at least 24 hours before filling the aquarium with water.
We take regular packaging styrofoam. The styrofoam does not have to be too hard; softer ones are easier to carve. Styrofoam is only needed as a frame; after the mortar hardens, it is practically unnecessary, resulting in a very strong, thick crust. We cut stones out of it with a regular knife. Then gently melt it over a gas stove to remove fuzziness. The main thing is that there shouldn’t be too much styrofoam and the layer shouldn’t be too thick; although silicone holds fine, if you overdo it, there is a risk that the structure might tear off and float up. First, glue the PVC plastic to the bottom and back glass of the aquarium. We glue it with aquarium silicone. Why plastic first? If you need to replace the background: silicone or mortar is easier to clean off plastic than off glass. Glue the carved styrofoam stones to the plastic using the same silicone. The frame is ready.
Now we take regular M-500 grade cement. Dilute it with water to a liquid slurry consistency. Apply the mortar with a brush in 2 layers with an interval of 5-12 hours. When applying subsequent layers of mortar, do not let the previous ones dry completely, and if they are dry, be sure to moisten them with water (otherwise it will crack and peel off). The 3rd layer is decorative. We apply it in places with a brush, in places with a sponge, and in places with a spatula (to give a natural stone look), while adding colorant to the mortar. You can use any exterior paint, as long as it is non-toxic. After complete (2 days) drying of the mortar, soak it in water for a few days to remove dust. After hardening, cement is completely non-toxic. The structure turns out to be quite durable, gets overgrown with algae nicely, which gives the background a natural look. It is also easily cleaned with a regular stiff brush.
Styrofoam stones. Suppose you need to set up an aquarium for African cichlids — lake inhabitants of rocky biotopes. Such a body of water must have a large number of grottoes, crevices, and caves, which are usually located along the back and side walls. But if you overdo it a little, the glass bottom can burst. The most ordinary styrofoam helps to get rid of these troubles, from which you can make artificial stones, grottoes, and caves.
First, the piece of styrofoam must be given the desired shape. To do this, unnecessary areas are burned out with a heated object (a soldering iron with an attachment, a spoon or knife heated over gas) and removed with a scalpel or razor. Then several through-holes or depressions that do not reach the front wall are made, into which a weight will be placed to stabilize the vertical position and weight down the workpiece so that it does not float.
By the way, the styrofoam stone can be glued to the bottom of the aquarium, placed on spacers or suction cups. But I think the weight option is more convenient. For example, you need to pull out the “stone”, well, say, to catch a fish. It is enough to push out the weight (which, by the way, should be in its groove with a small clearance), and the “stone” will immediately float up. To give the workpiece a natural look, you need to paint it with enamel, as it does not react with water. There is another way: lower the workpiece into a 5-10 percent solution of potassium permanganate and keep it there until the desired color is acquired. Then the workpiece is removed and lowered completely or partially into a solution of malachite green or methylene blue. The painted workpiece is allowed to dry a little and, after rinsing with cold water, placed in the aquarium.
You can install or glue flat (non-synthetic) roof slate to the back wall of the aquarium, and to it, in turn, attach the necessary relief elements.
Another (previously very popular) option for creating a background is dry dioramas equipped with their own lighting. They are placed behind the aquarium and consist of decorations using 3D elements (driftwood, peat, moss, bamboo, etc.). Make a box of thick cardboard, plywood, or other material matching the size of the aquarium’s back glass with a depth of 5-10 cm, paint its inner surface dark, and create a background inside it using roots, branches, tree bark, bamboo, stones, driftwood, moss, mounting foam, compressed peat plates, dark crumpled paper, painted styrofoam, etc., attached to the bottom.
The relief structure of the diorama visually gives the aquarium additional volume and expressiveness, and the box lid will serve as a place to store aquarium equipment or pots with moisture-loving plants. Additional charm is provided by independent lighting of the box cavity with small light bulbs inside, which will create a beautiful effect. I must admit that such dioramas look very impressive, however, creating them is a special art, mostly mastered by floral designers. Over time, the elements of dry dioramas get covered with dust, and getting to them is not so easy.
Using stones in aquarium design. Stone shapes.
