Whats a plenum?

[alexk3954]

I have been reading about deep sand beds and have heard about plenums multiple times. No one ever really expalins what the heck a plenum is though and I feel really confused.

Do you guys think that a 3-3.5 inch deep sand bed with sugar sized sand would be enough for NNR? Would a yellow watchman goby and some nassarius snails be enough to keep toxic gasses from building up?

 

[ChrisRD]

A plenum is a plate that goes under the substrate to create a void space underneath. They aren't very popuar these days and definitely not required for a functional sandbed. Personally, I wouldn't bother with one.

As for depth of the bed, I say use what you want. IME in a sensibly stocked, well run tank with enough live rock, good circulation and a good skimmer NNR is not really a big concern - even without a sandbed. Having a sandbed will add to the effect but IME it doesn't have to be all that deep to be effective.

If you want a deeper substrate for added diversity and/or to create a habitat for certain animals you might be keeping, by all means, go for it. Personally, I wouldn't be too concerned with the build-up of toxic gases in a sandbed (although the build-up of detritus/organics is an on-going debate/concern).

JME/JMO of course...