I recently set up a tank and wanted to have a raised section of substrate with a couple of caves for cat fish. In materials, the slate cost about £7 ($14).
To make one of these you'll need: A sack of slate chippings from your local DIY shop, 4 * thin
slate floor or wall tiles (or about 2 foot squared of tiles), aquarium safe silicon sealant, a mallet / hammer. 2 or 3 hours to spare.
- First wash the sack of slate chippings and go through them and pull out all the larger pieces that could be useful in building up the walls of the cave, dry them and lay them out on a clean surface. You'll only need maybe 5% of the sack, but there'll be a lot of small pieces in there that aren't much use.
- work out the foot print / surface area of the cave / rockery you want to make and lay out the floor tiles to cover that area. Draw or scratch on the surface of the tiles where you want the angles and cuts. Don't go for shapes that are too complicated.
- To cut the floor tiles you can use professional equipment, but if you are not too fusy about clean edges and have a couple of floor tiles in reserve.... put the tile on a flat surface / work top and move it so that the part of the tile you want to remove, is hanging over the edge of the work top with no support underneath. Lean heavily on the tile on the work top (or secure it with some means) and then with a large mallet, strike the overhanging part of the tile sharply, with follow through and the overhanging piece should break off roughly along the line. N.b, goggles and gloves would be a good idea here!
- from the pieces you've broken off, pick out pieces that look like they are a good shape and size for a cave roof / rooves. Break down more tiles if necessary if none of the shapes look right or are of the right size.
- It is important to mention that the next stage is to start using the silicon sealant. Once the silicon sealant is started, the whole structure must not be moved until it has cured. The whole structure can easily be built in one sitting and does not require you to let sections dry individually.
- You should now have floor tiles layed out that match the footprint of the cave / rockery. The next stage is to stick them together so they are solid like one piece. The easiest way to do this is to have two layers of floor tiles that overlap where the joins are and silicon sealed together. N.b, it doesnt' matter if this doesn't look fabulous, since it is only to provide support for the structure and will be buried beneath the substrate when installed.
Use other pieces of floor tile (e.g shards that dropped off) and silicon them across the joins in the floor tiles and silicon the joins themselves. It doesn't matter what shapes these are, providing they are broad enough to give a good surface area for the join.
- Now start building up the walls of your structure from the slate chippings. Try to pick pieces that will naturally interlock and form a natural structure and support without needing to be held or glued in place, since the structure will need to be able to support itself while it cures. The lower part of the walls will need to be maybe two chippings thick. As you add each chipping, put sealant on all the surfaces where the chipping touches other slate chippings / the floor tiles, so that when the sealant cures, the structure will hold itself together and be strong.
- The structure also has the function of holding substrate in place, so don't just build up the cave walls, but build up slate formations across the front of the footprint, to act as a sort of dam for the substrate when installed. This will also help to prevent ugly pieces of flat floor slate used as cave roof becoming exposed as substrate moves about. Don't worry about the rear of the foot print since it will be covered by gravel when installed.
- When you've reached the height where you want the roof, silicon the floor tile shard onto the supporting walls at all points where it makes contact. N.b, it's easier to shape your walls to an existing piece of shard that you've made, than try to break up a tile to match your wall shape.
- Now add more chippings on top with sealant. The chippings on top will help to hold substrate in place when the cave is installed in the tank and will give it a more natural look. Build on top of the cave as high as you want the substrate to be deep for the planting (if you get my drift).
- Add some more chippings to make the thing look more natural, some that stick up at angles, pieces that look like they've fallen off the main structure etc....
- Tiered sections can look very attractive when installed in the tank (e.g, staggered sections of different heights)
- Let dry.....
- Install.... n.b, make sure you lift and move the structure by holding securely the underneath of the tiles, giving as much support as you can and have an even layer of gravel / sand underneath the cave to evenly support the weight.
- With some of the left over slate chippings, scatter some around the front of the cave to give a more natural effect and scatter some at a distance from the cave.
p.s, disclaimer.. anyone making this does so at their own risk and I don't take any responsibility for injuries or damage sustained during the making of this structure... Good luck!