AERATING DEVICE FOR SALT WELL WATER 



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DEC JAN FEB MAR APR MAY 



WEEK ENDING 



Figure 3. — Salinity of Kewalo well water and amount of rainfall at Federal Building, Honolulu, 

 November 1958-May 1959. Rainfall data compiled by U.S. Weather Bureau. 



though the oxygen content of this aer- 

 ated water was as high as 2.34 ml./L, the 

 fishes tested {Ahiidefdiif^ Acanfhurus, 

 Arothron, Chaetodon, Parupeneus, Perva- 

 gor, and Zanchis) did not thrive; in fact, 

 many died within one or two days. In 

 a closed-circuit control tank the oxygen 

 level was maintained at 4.90 ml./L by con- 

 tinuous aeration with breaker stones, and 

 here similar test fish did very well. It 

 seemed obvious that an efficient aerating 

 device must be an integral part of the 

 pumping setup if circulating well water 

 was to be employed. 



AERATING DEVICES 



A cursory survey of the literature plus 

 correspondence with several aquarists re- 

 vealed that little was known, or published, 

 about the problem at hand. Specifically, 

 a device was needed for bringing oxygen- 

 poor water to the saturated state under 

 high-flow conditions, and so constructed 

 that oxygenation and circulation were con- 

 comitant features, eliminating any possi- 

 bility of fish mortality from exposure to 

 deoxygenated ground water. This require- 

 ment eliminated from consideration cer- 

 tain apparatus (Venturi systems, com- 

 pressed gas liberators, and agitators) of 



great utility elsewhere (Norris et al., 

 1960). The field of choice was narrowed 

 to sprays, cascades, and the like, where 

 the influx of water per se results in 

 aeration. 



Plans for the aeration apparatus began 

 to emerge when the physical conditions at 

 Kewalo were considered. Beds of spray- 

 ing fountains or shallow, baffled spillways 

 were precluded by limited ground space, 

 and the height of a tower from which 

 water could fall was limited by the pump- 

 ing pressure. Of various devices men- 

 tioned in the literature (Shaw, 1936; Betz 

 Laboratories, 1957 ; McKelvey and Brooke, 

 1959), a compact block of stacked perfo- 

 rated trays seemed to be the most promis- 

 ing. Oxygen- free ground water would be 

 pumped to the uppermost tray, from which 

 it would shower successively through sev- 

 eral lower trays, becoming saturated with 

 oxygen just as it reached an aquarium be- 

 low. The optima for tray spacing, number 

 and size of tray perforations, rate of water 

 flow, and tray number had yet to be 

 determined, 



EXPERIMENTAL AERATOR 



To discover the interaction of these vari- 

 ables a model aeration device was con- 



