Here's a picture, just for your reference:
http://doityourself.com/store/6377873.htm
Perhaps you could use something like this, only add a sheet of
plexiglass on top of the egg crate panel to hold gravel. Personally,
I would silicone the pipes and shelves together for stability, but I'm
kind of crazy that way.
You could design this so that water can circulate under the shelf to
avoid dead spots.
Geoff
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