Help with putting egg-crate under my substrate?

[ToolmanRR]

QUESTION: Will putting egg-crate on the bottom of a tank create little areas where circulation will not happen because the lower layer of the sand is contained/captured within the little squares of the egg-crate? Will that create places for "bad things" to happen? What if I cut slots into the underside of the egg-crate?

I purchased some egg-crate to put under my Aragamax Select substrate (0.5 to -1.2 mm sand) I'm thinking of putting it there to distrubite the weight of the live rock on the bottom of the tank.

 

[Entropy]

IMO it will make no difference. The bacteria and little critters will move from cube to cube without a problem. Assuming you are running at least an inch of sand (to cover the crate) it would be the same with or without it. The only issue you might find is if your flow patterns are not just right, sometime the egg crate might get exposed. It is not a huge deal, but kind of unsightly. Also make sure you leave a little space on the front and sides so the eggcrate doesn't show through the glass near the bottom edge. Keep in mind you can also cut out huge sections of the egg crate if there will not be rock in that spot. just leave the outer edge in one piece and it will hold itself together.

 

[bshumake]

Having done this exact thing with another tank I can tell you, don't do it. It was a waste of time and energy. It will crack or break under high load where there is no support. It will make tearing the tank down a PITA. My substrate turned into rock underneath the crate and I had to break it up to get it out.
Cut pieces of PVC will work just as well. Figure 3x 1" slices of PVC per rock. The PVC will distribute the rocks weight evenly across the circle instead of focusing it on the rocks pointy bottom spots.
The lower regions of the sandbed (as well as the innermost spaces of liverock) harbor anaerobic bacteria that convert the more noxious products of the Nitrification cycle into harmless components. Your creating "dead spaces" is just a natural part of any reef and nothing to concern yourself with. Only the uppermost region of a sandbed (1-1.5") has aerobic and facultative anaerobic bacteria (meaning they live in low O2 environments).
So party away. Return that eggcrate and get you something at the LFS. Tell em Reef Central sent ya. :beer:

 

[Mcubed]

What about just using some sheets of acrylic to help distibute the weight of any sharp edges? I would think that would take care of the "dead spaces" inside each cube issue.

 

[ToolmanRR]

<a href=showthread.php?s=&postid=14982639#post14982639 target=_blank>Originally posted</a> by Mcubed
What about just using some sheets of acrylic to help distibute the weight of any sharp edges? I would think that would take care of the "dead spaces" inside each cube issue.

As I was reading the reply from "bshumake" I had that same thought. But then I thought about the space under the flexigless. Even though it' would be an extremely thin area, there is zero curculation under it. I wonder if that water will harbor "bad things" after time.

 

[Gary Majchrzak]

IME/IMO

IME/IMO

eggcrate on the bottom buried in sand is a mistake.

tip: IME you can fill popular commercially built glass aquariums top to bottom front to back with liverock and they'll be just fine.