So what is the difference between a bead filter and a sand filter? Surely the same dangers that beset a sand filter are the same ones that a bead filter faces?
A bead filter for those that are wondering, is simply an upside down sand filter. Instead of having sand sitting at the bottom of a filter with water being pushed through it, a bead filter has floating beads with water pushed up from the bottom of the filter through the top of the filter.
In principle the operation is identical to that of a sand filter. Debris is trapped within a bead bed, as it would be within a sand bed. The beads are somewhat bigger than sand particles typically.
However, the big difference comes in terms of the backwashing operation. Instead of using water and an open backwash to clean a sand bed, a bead filter uses a dirty great big jacuzzi blower to blow a massive stream of air into the bead bed. As it does that, the beads become highly agitated and the bed is literally torn apart by the violence of the air being forced into the filter.
In the process the beads rub against each other and the debris is all shaken off into the water column. This dirty water is then discharged from the filter.
True, the same buildups that occur within a sand filter will occur in a bead filter. However, owing to a more efficient backwash process a bead filter can more effectively get rid of more solids. And because the blower is doing all the heavy lifting the process takes less time, uses far less water and build up within the bead bed is kept to a minimum if you do your homework and maintain the filter regularly (as you should anyway).