THE PUBLIC AQUARIUM 327 



water. Concerning the chlorine usually present in the water as 

 delivered to the bureau, a few tests were made using orthotolidine 

 indicator. In no case were more than 0.02 part per million of 

 chlorine present. However, at the time the experiments were made 

 very little difficulty was being encountered in the large aquaria, so 

 the tests are not very significant. 



SUGGESTED PROCEDURES FOR CHLORINE REMOVAL 



Having decided on a means for counteracting the chlorine in city 

 water, one next has the problem of finding a means of introducing 

 the chemical chosen into the water supply. For aquaria using large 

 amounts of water (100,000 gallons a day) it seems best to insert 

 directly in the main a mixing chamber consisting of a large pipe 

 filled with coke or other similar material. A solution of the chemi- 

 cal is then pumped into the main before the water reaches this mix- 

 ing chamber. To do this requires a very small piston pump suitable 

 for handling;, say, 0.01 to 0.03 gallon of solution a minute and 

 capable of continuously operating against a back pressure of 50 

 pounds. Such a pump can be purchased or can be built easily. It 

 should be calibrated when working against the main-line pressure 

 and the strength of solution made up to suit. If the variation in 

 amount of water used is relatively small, no control of this pump 

 should be needed, and the only attention required would be lubri- 

 cation of the small electric motor and pump and refilling the chemi- 

 cal-supply tank. The size of the pump and the concentration of 

 the solution should be such that the supply tank need be refilled very 

 seldom. 



For smaller aquaria using a continuous flow of water it will be 

 simpler to use a mixing chamber consisting of a trough with baffles. 

 This trough is mounted above the aquaria and delivers its effluent 

 to the aquaria by gravity. The chemical may be pumped into the 

 trough as before or may be fed in by gravity from a storage tank 

 above the trough. If it is desired to make large variations in the 

 flow of water used, it may be desirable to use a machine designed 

 for such treatment.'' 



For aquaria in which water is not circulated continuously, but 

 which are drained and refilled periodically, the problem is merely 

 one of adding the required amount of chemical and stirring. As 

 mentioned earlier, the necessity for treatment disappears in small 

 household aquaria where it is possible to let the water stand for a 

 time before the fish are introduced. 



The cost of treating 100,000 gallons of water a day with sodium 

 bisulphite should not exceed 10 cents a day for chemical and 20 

 cents a day for power if the piston pump mentioned above is used. 



" Chemical Dosins Apparatus. Cliarlrs F. Wallaco, assignor to Wallace & Tierman 

 Products (Inc. I, Newark, N. J. U. S. Patent No. 1593109. 



4231°— 29 6 



