Egg Crate Under Rockwork ?

[hillbillyreefer]

I've got three tanks with, one without. One with has only about 1" of sand and sometimes the egg crate is exposed by the flow, looks terrible. One has about 3" of sand I've never seen the egg crate in the tank, I like it. One just has the rock sitting in the EC no sand. It doesn't look very good, I thought it would cover over in coraline, but hasn't in 2 years. It is also a pain to syphon detritus out of at water change time. The BB is great for syphoning at water change time, out of the two without sand I like it the best.

A long story short, if you are going BB don't use egg crate, if your going to use sand then use it, IMHO.

[mike31154]

I cut some large diameter ABS pipe into sections to support several large pieces of live rock. Drilled random holes in the sides for circulation. I should have siliconed them on to the bottom glass though, since they've shifted a bit on me while I was messing around rearranging stuff. Next time I start up a tank, I'll likely do the same or just cut semicircular sections as shown in the photo below. By using sections of ABS like this, you have more flexibility as to placement and the entire bottom doesn't have to be covered as when you use eggcrate, allowing for better access and circulation. Another advantage is you can customize the height and profile of the ABS pieces to better suit the shape of a particular rock.

[kien]

I place my heavy rocks on a sheet of acrylic. The parts that get exposed by the fish and powerheads typically encrusts with coraline so it blends in with the rock and tank bottom if it has been exposed too.

[hippo!]

I use it on all my tanks. Cheep insurance IMO.

[viperfish]

a couple of inches of sand will cushion the rocks from creating any stress concentration on the glass. My only fear with eggcrate is that it's just another place to trap debris that can't be siphoned out and sand sifters won't be able to get to it. I guess it would help in the event of a rock slide but I've never heard of stationary rocks on a sandbed cracking glass.

[Aquattro]

I would never put rocks on sand again, I had a tower collapse as the sand shifted under it. Probably induced by some livestock, but it was a mess. Didn't hit glass, but from now on my rock sits on solid footing and sand goes in second.

[viperfish]

I stack mine very carefully, and a little bit of DD putty between them ensures nothing is going to move. I also place some putty anywhere a rock might touch the glass on the back to reduce the stress concentration.

[mark]

when I had a DSB built boxes with egg-crate and zipties for the rock to sit on so the bottom 4" wasn't buried in sand.

With the new tank and BB, rock just sits directly on the glass.

[DiverDude]

Some interesting points have been made.

I was only planning on putting small(ish) sections of Egg Crate (EC) under the rock and not over the entire bottom. I'd like snails, my sea star, bulldozer shimp/Goby to be able to dig away without the impediment EC might cause.

The though was that where there was rock, the EC would displace stress and PREVENT any/all of the aforementioned critters from undermining it and causing issues.

The acrylic is a really good idea too as is the ABS -but I've been told not to put ABS in a tank but I'm sure a few bits under sand wont' hurt anything.