Bead filters, utilizing floating plastic media, have been used since the mid 1970's as biofilters to support high density rearing of food and game fish. Although successful, the operation of these early air washed filters was poorly understood and their use was limited. In the late 1980's, work at Louisiana State University demonstrated that a hydraulic washed bead filter was capable of supplying solids control and biofiltration for a high density catfish rearing system.
These results stimulated additional academic interest in bead filters. Development of mechanically washed units (U.S. Patent Nos. 5,126,042 and 5,445,740) that were compact and simple to operate overcame many of the operational difficulties experienced by earlier designs.
Shortly thereafter, the favored "bubble-washed" or "hourglass" configuration (U. S. Patent No. 5,126,042) was developed and tested for use on outdoor ponds. Since 1989, bead filters have been tested on systems holding food fish (such as tilapia, catfish, striped bass, trout), along with a wide variety of specialized applications (including ornamental fish, alligators, crayfish, crabs, oysters).
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