The leaching of wooden tanks and the concrete troughs and sump 

 was accomplished by recirculating tap water through the system for a month. 

 During this period minor changes were made to increase the velocity and de- 

 crease the water depth in the return troughs, and to increase the efficiency 

 of oxygen exchange and thus the holding capacity of the entire system. The 

 sand filters perform satisfactorily. Their effectiveness was particularly 

 apparent after the first addition of muddy (15-inch Secchi disc reading) sea 

 water. After several days of recirculation, the clarity equaled that of tap 

 water. Periodically the beds have to be backf lushed with large volumes of 

 tap water to float off the accumulation of particulate matter. This is always 

 followed with a salt-water backflush to avoid dilution problems. 



Sanaples of the water are analyzed three times weekly for salinity, 

 oxygen, ammonia, nitrate, nitrite, phosphate, pH, alkalinity, carbon dioxide, 

 protein, and carbohydrate. 



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