Originally Posted by blrrobinson21
Well siphoning and replacing was kind of what I was thinking about. Here's my next question. Would it be ok to leave the bed filter in place and put a 2 or 3 inch sand bed on top of it leaving CC under it?. That would leave about a inch or less of CC. I cant actually use the bed filter with sand can I?
I wouldn't place sand on top of the undergravel filter. What I would do is leave the CC under the undergravel and a little over, so you end up with a 1 1/2 to 2" deep layer of CC. Then covered that layer with fine black fiberglass mesh (available at your local hardware store). The mesh serves two purposes, one it prevents sand-dwelling organisms and sandgrains penetrating into the lowest level of your DSB
; since this in an anaerobic area, you don't want those creatures in there, and you want to maintain the pockets for gas exchange. And two, it prevents the courser CC from working its way to the top of the sandbed. Additionally, because this anaerobic area is acidic, the CC will break down over time adding calcium to your water which will be beneficial for coral growth.
Over the top of the black mesh place a 1 1/2" to 2" layer of courser sand (still the fine sand), but the courser grade. then layer a 1/2 to 2" layer of fine sand on top (I have used both the bagged live sand - which really only supplies bacteria, and dry sand which is then "seeded" with a couple pounds of real live sand aquired online or from your LFS
As far as the deep sand bed, it will have to be maintained; which you do by buying the proper creatures to maintain it. NO sandsifting gobies or sea stars (as they consume the beneficial microorganisms that are contained in the sandbed). Once established, the DSB
must remain undisturbed, as it will build toxic conditions in the deeper anaerobic layers, and disturbing this layer can crash your tank. So after you put down the CC layer and the black mesh, place your LR
directly on the mesh; burrowing fish will not be able to get below the mesh to topple your rockwork, and the CC will cushion the bottom glass from the LR
. Never vaccum or stir a DSB
, except very lightly across the top if needed.