Fluidized Bed Filter?

What exactly does a fluidized bed filter do?

 

Its a simple semi floating sand bed and on the grains are where the denitryfing bacteria builds up and lives to provide the filtration of the systems. They work very very well Great idea and simple as dirt to use.. I ran a 100 gallon sps tank on one for several yrs until I tore the tank down and gave it to my son he still runs it though. A DSB or U/G filter in a bottle so to speak

 

I run one too! ;D

 

Yes you do..

 

So is there a crate or something that goes underneither the sand? And does the sand actually 'run' through tubes through the filter? I find this interesting.

 

All you are doing is running water across the sand making it tumble. I run one of these.
Red Sea Merlin Fluidized Filter
Well I actually run three of these but the other two have carbon in one and phophsate remover in the other one. ;D Nice little units they have their own flow control built in.