Rock-scaping - securing rock together

[kimber45]

What about a solid base below the sand, what have people used to elevate the rocks a bit off the bottom of the tank?

i was in same situation with my nano. i ended up installing eggcrate on bottom then siliconed the bottom layer of rocks to it. note in the pic i had 2 layers of eggcrate, i only used one in the final assembly.

from there i used fiberglass driveway markers from homedepot and epoxy and also fishing line to secure rock work.

 

[Saltcity]

I used 3/8" plastic toilet supply line and some hold fast epoxy. I use zip ties around it untill the epoxy sets up.
This is one of my arches.... I pick stable pieces for the bottom and make sure I "squish" them dowm through the sand close to the glass.

 

[JeffBoyRD]

Nice arch Saltcity. Does the "toilet" line go through the rock? Did you drill it? Is it one piece through the entire arch? Dumb question: What is hold fast epoxy? Is that a brand? Where did you get it? Thanks.

 

[Saltcity]

Nice arch Saltcity. Does the "toilet" line go through the rock? Did you drill it? Is it one piece through the entire arch? Dumb question: What is hold fast epoxy? Is that a brand? Where did you get it? Thanks.

I just drilled in the rock a couple inches... gotta be careful because some of this rock is brittle. I stick a piece of the plastic line in one rock 2 inches and leave 2 inches sticking out to "thread" the other rock down on. Hold fast epoxy is just two part epoxy that is sold at most saltwater stores or you can get it online at Fosters or other places. You mixe the two parts and it hardens in 30 mins. I also use some silicone here and there. Takes time but it usually looks better than just trying to stack rocks or bridge rock to rock.

You can't tell but the lower part of the left column has a rock sticking out towards the camera.... it will be a smaller arch