"Rock wall' made of styrofoam and sand

davidcalgary29

New member
While I'm waiting for my jarquariums to go through their algae cycles, I thought I'd start planning my final build for the next few months: a "tidepool tank" in a Fluval 13.5. What I'd really like to do is have a rock wall, with shelves, on the left side of the tank made to mimic the oolitic sandstone I often see in Bahamian tidepools (as seen below). The sandstone is often very weak, layered, and can be easily broken. The structure may go around a corner, but I think putting it all across the back would be just too much.

I was planning to sculpt part of a styrofoam crate and glue sand on it. Buoyancy will be a problem, so I'll have to keep part of the bottom of the crate and put sand on it to weigh the structure down. The rest of the tank will be very minimal -- no rock, some alga (mermaid's glass/fan, when available), little coral, and some inverts. And perhaps a Royal Gramma or two down the road. Does anyone have any tips for sculpting styrofoam for use in an aquarium? I've seen a few YouTube videos, but the results look kind of ugly, which is something I'd like to avoid.
 

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Duality

New member
About 10 years ago I did a foam back wall. I also glued sand and pieces of rock to the structure. I found shortly after cycling that the foam was a horrible idea. My crabs, urchins, and snails would pick or eat chucks foam off the wall. I would find sand size foam bits on the water line of the tank and sump. The bits filled my sock filters and were even found in skimmate
 

davidcalgary29

New member
Yeah, I wrote that post before bed last night and might have to reconsider. I've watched a few more foam-sculpt vids and have to say that the results are all pretty ugly, although the posters seem to have had fun making them. I really did want to try to make a shelf fairly high up the wall, though, so that it could create a darker, shadier spot underneath.
 

Timfish

Timfish
Premium Member
How about a piece of acrylic for the base structure then use casting acrylic and sand to make shelfs or tunnels using sand casting with araganite sand. Then glue the casting to the acrylic backing.
 

davidcalgary29

New member
How about a piece of acrylic for the base structure then use casting acrylic and sand to make shelfs or tunnels using sand casting with araganite sand. Then glue the casting to the acrylic backing.

That video was everything that I didn't know that I needed! I will definitely keep it in mind when I want to make that homemade bardiche or halberd for the zompocalypse, but it will probably just result in unnecessary explosions, maimings, and/or burnings if I try that in my basement.

I see that I can get E-Marco 400 in Canada. I'll probably get some of that and use that directly or coat some styrofoam pieces with it. In fact, I could probably use a styrofoam carton as a flask, fill it with sand, and pour the mixture into a negative mold, creating the structure. The shape might actually hold if I use damp sand, although I suppose it would be better to make several small pieces and seal them together.
 

Michael Hoaster

Registered Seaweedist
Premium Member
Buoyancy is a real issue, so the thinner you make your fake wall the better. Looking at the pic, you may like the black pond foam that I used. It comes out grey. One way to combat the ugliness is to use a power sander to sculpt it into exactly what you want. I imbedded plastic bottles into mine, for caves for Royal Grammas.

My fake wall thread: http://reefcentral.com/forums/showthread.php?t=2403722
 

davidcalgary29

New member
Buoyancy is a real issue, so the thinner you make your fake wall the better. Looking at the pic, you may like the black pond foam that I used. It comes out grey. One way to combat the ugliness is to use a power sander to sculpt it into exactly what you want. I imbedded plastic bottles into mine, for caves for Royal Grammas.

My fake wall thread: http://reefcentral.com/forums/showthread.php?t=2403722

There are some fantastic builds in that thread, and it's certainly given me a few ideas! Thanks for that.
 

rhkingsfan

New member
Here is a link to my foam rock build:

http://reefcentral.com/forums/showthread.php?t=1858191

I actually enjoyed it. Ran the tank for probably 5 years but tore it down for a remodel to the house. I didn't have issues with chunks being taken out but I also didn't have an urchin. I didn't have the patience to do what some of the others did. All i used was eggcrate, silicone, great stuff (for ponds), epoxy and sand; I though it came out great.
 
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