| Yea Wit this is a different system that what I am familar with in regards to plenums. I ran a plenum on a tank for several years with no problems, but it was a different animal then what you are discribing.
The plenum had black acrylic sides (to keep light out) and a mesh top simular to what you discribed. But on top was very coarse gravel. I would say three to four times as thick as CC. and it was about 4 inches high in total. Water flow was directed at the plenum and it kept the whole 3 inches of gravel areobic (well oxygenated), lots of bugs and life, moderate dentirification, and an ammount of elemental replenishment. This plenum was taken off Jauberts Plans (him and another fellow invented it)
The system you are discribing sounds like a blend of the plenum and DSB concepts, so I would imagine that it would have all the goods and all the bads of a dsb. One thing that seems to be fixed possibly is the flow restrictions a DSB has.
not much help but best I got my friend
MIke |