44 METHOD OF DESTKOYING ALG/E IN WATER SUPPLIES. 



copper sulphate renders it fatal to pathogenic forms peculiar to water, 

 while the saprophytic or beneficial bacteria are unaffected, the method 

 is particularl}- well adapted for this purpose. 



Definite knowledge in regard to what organisms are present, the 

 constitution of the water, its temperature, and other important facts 

 are neciessar}^ before it is possible to determine the proper amount of 

 copper sulphate to be added. A microscopical examination thus 

 becomes as important as a bacteriological or chemical anal3'sis. 



So rule for ddenninlng the amount of copper sulphate to Ije added 

 can he given. Each hody of water must he treated in the light of its 

 special conditions. 



The cost of material for exterminating algaj will not exceed 60 to 60 

 cents per million gallons and will usualk be less. The destruction of 

 pathogenic bacteria requires an expenditure of from $5 to $8 per 

 million gallons, not including the cost of labor. 



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