A solution to the problems associated with conventional raceways (poor solids removal and degradation of water quality from the inlet end to the exhaust end) is to convert a raceway into a series of counter-rotating mixed-cells. The concept of a mixed-cell raceway (MCR) was first proposed by Watten et al. (2000) to eliminate metabolite concentration gradients, increase current velocities, and improve solids scour at low water exchange rates. A MCR is created by installing inlet jets that cause a series counter-rotating cells and each cell has its own center drain for solids removal; approximately 20% of the total raceway flow exits the floor center drains. The inlet jets are a series of vertical pipe sections with jet ports located in the corners of each cell and water is directed tangentially to create rotary circulation. Experimental units have been installed at a commercial and a university research location to determine the effectiveness of the new design (patent pending).