Rock caves/decor from foam and concrete?

[Daven]

Ive wanted something taller/bigger to split my tank up a bit more for my mbuna cichlids, but could never find anything tall enough. I have around 16 of those "Underwater Galleries cichlid stones" which i think are great, but pricey. I like that they dont displace really any water like real rocks, and theyre very light so i dont have to worry so much about falling. So instead of buying another large pack of those, i was thinking of doing something like the rock backgrounds ive seen people make but instead make a mountain. I would like to displace as little water as possible, and create as many caves/hallways for the fish to occupy as well. I beleive my tank is 21" tall (75 gallon), so im hoping to reach more towards the top to split the tank more into two sides for territories.

Any ideas? Maybe first i should ask how it is done without posing any risk to the fish?

 

[Oto]

Have you seen the 3D backgrounds made with foam, silicone and concrete? I haven't made one, but from what I've seen, it would be very easy and attractive (and not too expensive) to make caves as part of the background. You do have to be careful with the concrete: it messes with the pH so it needs to cured for a while.

Never mind, I just saw the top part of your post.

 

[Oto]

Also, if you have any wide diameter PVC pipes or clay flowerpots, those would work well. I have a few flowerpots with a blood parrot once, and it was always hanging out inside them.

 

[Oto]

I remember seeing a tank arranged with flowerpots stacked on top of one another with half pots on the ends to keep the arrangement more evenly stacked. You could do a layer of these up to the top, and it shouldn't displace too much water.

 

[Daven]

I had seen the backgrounds a few times. But I'm not sure how to make it so it won't affect the water. And I do have plenty of pvc at work I could use, but thy aren't very natural looking. Maybe if I used them for some caves in the rock pile or something


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[aclark]

I was thinking about this last night and it might be hard to make sure all the caves and cut outs get evenly coated in concrete and sealer. What if instead you molded it out of clay and kiln dried it? Would be just as safe as a terra cotta pot and you wouldn't have to worry about exposed foam or concrete in the tank. Probably easier to get the tunnels molded to you liking.

 

[Daven]

I had thought about that too. I don't know anything about clay lol just mold a certain kind and bake in the oven? Lol

What I was thinking for the concrete was maybe making it in different pieces with the tops exposed so I can coat them and then have it so it assembled together afterwards


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[aclark]

I would guess most oven baked clays would be aquarium safe. Don't quote me on that, and do your own research. Might even be able to use chicken wire or something to mold the clay around to add structure to it. If its covered by the clay you shouldn't have leaching issues once cured.

 

[Daven]

I would guess most oven baked clays would be aquarium safe. Don't quote me on that, and do your own research. Might even be able to use chicken wire or something to mold the clay around to add structure to it. If its covered by the clay you shouldn't have leaching issues once cured.

Yeah hopefully someone sees this who has done something simular before. Im more or less looking for ideas and tip like you have given me so far! Thanks