44 METHOD OF DESTROYING 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 particularly 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 necessary 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 analysis. 



No rule for determining the amount of copper sulphate to be added 

 can be given. Each body of water must be treated in the light of its 

 special conditions. 



The cost of material for exterminating algae will not exceed 50 to 60 

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

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

 million gallons, not including the cost of labor. 



O 



