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fairly effective. Tests showed that the use of 1=2 cubic centimeters of the 

 chemical with 10 grams of clay soil per gallon of pond water caused the finely 

 divided soil to remain long in suspension.^ The chemical had the effect of a 



■'■The material was mostly unweathered subsoil mined approximately 6 miles south 

 of the hatchery in an area having tight, alkaline clay soils. 



'dispersing agent, probably by forming a protective coating around the soil 

 colloids and greatly retarding their flocculation. The substance is relatively 

 inert and has no obvious effect on fishes, plankton, insects, or other aquatic 

 organisms. Four ponds were treated with combinations of clay and the chemical, 

 and two additional ponds were treated with the chemical only (Table 7). It 

 was found, however, that the turbidities could be controlled only within broad 

 ranges. This was believed partly due to the individual characteristics of the 

 •ponds, and also to a lack of uniformity in the soil material. Such large 

 quantities were involved that it was impossible to standardize the soil be- 

 yond the crude selections made in the field. The soil was trucked to the 

 ponds and finely divided in 55 gallon drums by use of water pressure from a 

 two-inch pump. The sodium silicate was also added to the barrel, and this 

 highly turbid mixture was then pumped into the pond. The original turbidities 

 were high, but they lessened over a period of weeks until additional treat- 

 ment was needed. 



Since there was some doubt that the use of the chemical would prove 

 successful, it was decided to muddy an equal number of ponds by use of carp. 

 Five adult carp were added to each of six ponds (Table 7), The possibility 

 of reproduction was eliminated by using only males or females together in 

 the same pond. Attempts were made to control the turbidities by the weight 

 of carp used in each pond and by the amount of clay soil added to the ponds. 



