The modern scientific techniques of radioactive labelling and automatic digital computation were used in an experimental study of a new theory of rapid filtration. The algae Chlorella and Scenedesmus were made radio-active and suspensions of these algae were filtered through a sand column. The distributions of the algae deposited in the filter pores were measured with a scintillation counter, and the resulting data was used to check the validity of the theory. The computer computed information on changes in water quality and head loss in the filter. This information was compared with experimental results and provided information on filter operation that could be used for rational filter design.