DIY Rockwork centerpiece help.

[kittyhazelton]

I dunno if anyone has tried this or not, but I want to create a good-sized centerpiece/rockwork ledge for a tank that will be a FO saltwater setup.
A friend of mine has created interesting aquarium decorations using sand/gravel and plastic resin, and I am wondering if I could do the same thing using styrofoam as a simple shape structure, and then using the resin/rock/sand/gravel mix to coat it and create the look of the structure itself, and when it dries completely I'll pull the foam out of the inside of it leaving it a big hollow cavelike structure.
Has anyone done anything like this before? would it be able to withstand the corrosive properties of saltwater? any ideas/suggestions are welcome.

 

[Cyclop3000]

Sure, the resin will be fine in saltwater. You just have to be careful and pick a resin that will not bleed chemicals in the water, even when cured some resins are toxic. And it's a fine idea, by using rocks and sand you won't need to paint the resin, as some paints can also be toxic.

Oh one more thing, do mention your local expert that the resin will need to sink, some resins will not sink in the water and just float on the surface, which could be a little annoying

Have fun!

 

[kittyhazelton]

Sure, the resin will be fine in saltwater. You just have to be careful and pick a resin that will not bleed chemicals in the water, even when cured some resins are toxic. And it's a fine idea, by using rocks and sand you won't need to paint the resin, as some paints can also be toxic.

Oh one more thing, do mention your local expert that the resin will need to sink, some resins will not sink in the water and just float on the surface, which could be a little annoying

Have fun!

The stuff my friend uses is fish-safe to my knowlege... he's used it in his discus tank with no ill effects. I am pretty sure the stuff sinks, and if not I would assume that the wieght of all that sand and rock would help it sink anyway. he makes fake plant decorations and rocks and such with the stuff, not sure what brand it is though. I'll be getting more details from him.

 

[schaadrak]

Have you looked into making aragrocrete? I'm not sure how much the resin costs, but aragrocrete is just made with Portland cement and aragronite sand. It should be a lot closer in composition to the natural rock, too, and become "live" rock after a while. The major draw back is the wait. The time it takes to fully cure is around 4-6 weeks.