[BubbaWPB]

I've read a lot about DSB and plenum. Would there be any advantage to doing a partial plenum - say two 1' x 2' sections? I'm thinking the advantage would be that I would not have to hang the rocks off the side of the tank, since rocks sitting on the plenum area allegedly cause problems.

Has anyone tried to mix the DSB and plenum method in the same tank?

[ppurcell]

I've read Jaubert's Live Sand booklet and what Anthony Calfo/Bob Fenner (C/F) have written on the subject. A DSB and plenum are complementary; however, Calfo and Fenner indicate (I'm heavily paraphrasing here) that there aren't any studies which demonstrate that a plenum provides any benefit for the home aquarium as they would more naturally apply to very large systems. They go on to say that a plenum does't seem to do any harm either.

So, that being said, I built my plenum before I read the C/F book. Both C/F's and Jaubert's recommendation is to minimize the contact points on the sand bed. I accomplish this by placing a few small rocks on two stacked pieces (at offset angles) of eggcrate which sit in the sand bed, barely covered by sand as the reef foundation. This seems to allow nearly all of the sand bed to be in contact with moving water permitting water flow into the bed without requiring the construction of a suspended reef. One of the other suggestions from C/F is to use branch rock (staghorn rubble) as the base layer for building your reef as it will greatly reduce the contact points your reef makes with the LS/DSB.

Of course since there are animals in the tanks moving the sand around, there are some corners and tops of the eggcrate which always seem to be visable. So, I'd kinda lean towards the branch rock approach and probably wouldn't bother with building the plenum at all if I were going to start over.

I don't really know if this is the best way or even a good way to go about this; I'd be happy to hear other folks opinions too.

[Steven Pro]

I find it easier to simply use a standard deep sand bed without plenum and simply elevating the liverock structure above the sand bed. I typically place dry, dead rock down onto the tank bottom and then fill in around them with the sand. Then place my live rock on top of the dead rock when I build the rockwork.

[BubbaWPB]

My new tank has a base of 7' x 2' ... lots of room on the bottom. I've read about plenum and DSB. The good thing is that both work, so I'm sure it would be hard to go wrong with either approach. I just wondered if anyone had tried a combo approach... and if there would be any theoretical advantage.