122 " The Philippine Journal of Science me 



SUMMARY AND CONCLUSIONS 



The chemical purification of swimming pools has been studied 

 with special reference to the action of copper sulphate and 

 chloride of lime. 



The work was done on water that was turbid, high in bicar- 

 bonate alkalinity, and bacteriologically unsatisfactory. 



Copper sulphate was found unsuited to a water of the type 

 used. 



As much as 2 parts per million of available chlorine, adminis- 

 tered as chloride of lime and at a single dose, failed to keep the 

 bacterial content of the water within safe limits due to the rapid 

 disappearance of available chlorine from the water. It was 

 only with daily additions of chloride of lime that adequate puri- 

 fication resulted. With this procedure, however, it was found 

 possible to keep a pool bacteriologically clean for two weeks 

 without change of water. There were noted no objectional 

 features arising from the large quantities of disinfectant added 

 (daily additions of 0.5 part of available chlorine per million parts 

 of water). The advantages of the periodic administration of 

 hypochlorites in small quantities over the addition of the same 

 total amount at a single dose are discussed. 



The factors influencing chlorine consumption and the chlorine- 

 binding power of various substances were studied. The tempera- 

 ture of the water and the amount of light a pool receives greatly 

 influence the decomposition rate of hypochlorites. Body products 

 have an especially great binding power for chlorine, a fact that 

 emphasizes the need of great personal cleanliness among users 

 of swimming pools. 



Determinations of dissolved chlorides or of oxygen consump- 

 tion give little or no indication of the purity of swimming-pool 

 water. The tests that apparently give the most information are 

 determinations of available chlorine and of chlorine-consuming 

 capacity. 



In the purification of the water of swimming pools each case 

 should be considered as a separate problem, since the procedure 

 adapted to one may be entirely unsuited to another. Chemical 

 study is as necessary as bacteriological to obtain the best results. 

 The minimum quantities of hypochlorites necessary to maintain 

 an excess of available chlorine should first be established by 

 experiment, and these quantities should be administered at short, 

 regular intervals. Once the dosage proper for ordinary circum- 

 stances is known, it becomes an easy matter to keep a pool in 

 sanitary condition. 



