170 



EUGENE L. NAKAMURA 



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I^TGURE 1. — Skipjack-holding pool, 23 feet in diameter and 4 feet deep. Behind the pool on the left 

 is the aerator resting on the sump, and on the right is the pumphouse. The well, which cannot 

 be seen, is between the pool and pumphouse. 



sible. Since the trays were set 2 inches 

 apart, the area between them was inacces- 

 sible for cleaning. Cleaning was desir- 

 able only because of the deposition of 

 rust and not because of algal growth, 

 which was inhibited by the enclosed situa- 

 tion of the trays within the aerator. 



The aerator efficiently oxygenated the 

 water (over 95 percent saturation), but 

 did not adequately rid the water of carbon 

 dioxide components. Excess carbon diox- 

 ide in the water caused the pH to be lower 

 than that of normal sea water. The pH 

 was 7.4-7.6 as compared with 8.1-8.3 in 

 the open ocean (Sverdrup, Johnson, and 

 Fleming, 1942). By rerouting the water 

 through the aerator several times, the pH 



could be raised to 8.1 in 40 minutes, but 

 this recycling was not practical. 



In order to remedy these undesirable 

 features of the aerator, plans for a replace- 

 ment were made. The trays were to be 

 spaced to permit cleaning. Better ventila- 

 tion throughout the aerator was to be pro- 

 vided. Smaller but more numerous per- 

 forations were to be made in the trays so 

 that the elimination of excess carbon diox- 

 ide would be improved. 



The necessity of enclosing the pool in a 

 building became apparent for two reasons. 

 First, the entrance of direct sunlight into 

 the pool could be controlled to reduce or 

 eliminate algae. In the outdoor pool, al- 

 gae grew rapidly, and frequent scrubbings 



