84 1'he Philippine Journal of Science 



The general results of the experiments, as far as the bacterial 

 count is concerned, may be summarized as follows: 



1. When no disinfectant was added, there was a steady increase in the 



number of bacteria in the swimming pools. This increase was exceed- 

 ingly high on the last day of the week the water was used. 



2. When the disinfectants were used, the bacterial curve was lowered and 



often became more irregular. 



a. Copper sulphate applied at the beginning of the week permitted an 



increase throughout the week, but sometimes a slight reduction 

 occurred. 



b. Calcium hypochlorite applied once a week showed good effects at first, 



but permitted too large an increase of bacteria toward the end of 

 the week. A daily addition amounting to 0.25 part of available 

 chlorine per million parts of water permitted a considerable increase 

 of bacteria, while 0.5 part gave the best results. 



When the comparative costs and disinfecting power are con- 

 sidered, antiformin and copper sulphate are not as valuable as 

 calcium hypochlorite. The latter, when added daily in amounts 

 equivalent to 0.5 part chlorine per million parts water, is recom- 

 mended for the disinfection of these swimming pools, as it is 

 the best and most economical means of keeping the number of 

 intestinal and other bacteria within safe limits throughout the 

 week in which the same water is used. 



