Faux rock building and safe treatment

[SJC]

I want to build a large rock background for a 55 gal tank. If I use styrofoam to carve and paint, what is best material and good supplier? Thanks. New to hobby.

 

[Lepisosteus]

Use expanding pond foam, egg crate, and sand. You can add braches into the foam if wanted.

 

[SJC]

Use expanding pond foam, egg crate, and sand. You can add braches into the foam if wanted.

Is the pond foam inert in hard water. Do you know a brand? Thanks

 

[Lepisosteus]

Is the pond foam inert in hard water. Do you know a brand? Thanks

It’s inert in a reef tank so likely fine in most/all systems. I used aquascape pond foam.

 

[SJC]

Thanks!

 

[pacu mom]

 

[DrownedFishonFire]

question- does this stuff fight to float to the top? The pond foam stuff? Lepisosteus if I applied this to use to create a cave system for bottom of the tank? Not just side of the tank?

 

[duanes]

To fit one of the commercial background together (after cutting it into 3, and trimming it back to thin it out)(it took up a lot of space) I used Great Stuff to fill in the cutting gaps.

https://hosting.photobucket.com/albums/i97/dstuer/2384/stand/130/.highres/IMG_7051_zps48335ad9.jpg

I figured algae would help in time, evening out the contrasting colors
The background was very buoyant, and had to be securely afixed with silicone to the tank back or it would shoot out of the tank like a breeching whale.
And don't leave any gaps for fish to get in a hide behind it either.
Caves solidly affixed could be problematic, if a fish you are trying to catch hides in them, or dies in them secretively..