Aquaculture Systems Technologies, (AST) product line features ten propeller-washed bead filter models with bead capacities ranging from 3 ft3 to 100 ft3 and seven bubble-washed bead filter models with bead capacities from 1/4 ft3 to 10 ft3. These filters are often referred to as bioclarifiers for their ability to perform both biological and mechanical filtration in a single unit. Bead filters operate very much like submerged rock beds or undergravel filters, with the added advantage of easy cleaning.
Bead filters are generally classified as expandable granular biofilters and are distinguished by the use of buoyant granular media. The packed bed of plastic beads, through which water from the tank passes, captures solid waste (100% of particles >50 microns and 48% of particles 10-50 microns). Simultaneously the beads provide 400 ft2 / ft3 of surface area for the attachment of nitrifying bacteria, which metabolize dissolved nitrogenous waste.