WATER MANAGEMENT FOR MARINE AQUARIUMS 



13 



water in the tanks of the aquarium at the 

 Scripps Institution of Oceanography is 

 changed once every 3 to 5 hours, and this 

 has proved satisfactory. At tlie Plymouth 

 Aquarium, however, a turnover of 

 slightly more than four times a day was 

 barely adequate (Wilson, 1960). At the 

 Amsterdam Aquarium, an entirely dif- 

 ferent situation prevails, with the water 

 in each tank being replaced on an average 

 of only 11/^ times a day (Sunier, 1951). 

 We believe that for most laboratories and 

 aquariums, an ideal rate would be 20 to 24 

 changes of water a day (see Addendum). 

 A cardinal, though unproven, principle 

 of sea-water management is that the 

 greater the volume, the slower its rate of 

 deterioration. General aquarium experi- 

 ence, Avithout any doubt, abundantly sup- 

 ports the corollary principle that the ratio 

 of volume of sea water to volume of an- 

 imals kept in it should be as large as pos- 

 sible. Wilson (1952) has reported an in- 

 formal experiment that was dictated by 

 World War II at the Plymouth Aquar- 

 ium : "During the war when most of our 

 big tanks were broken and empty, the in- 

 habitants of those which remained did 

 noticeably better, and delicate organisms 



survived longer than they did before the 

 war, or do now, and sometimes even bred." 

 The greatest ratio ever maintained in a 

 large sea-water circulation seems to be that 

 in the Amsterdam Aquarium, where the 

 tanks containing the marine animals com- 

 prise but one sixth of the total volume of 

 the system. One way of lengthening the 

 useful life of a volume of sea water is to 

 divide it into two equal parts and alterna- 

 tively "rest" half of the water in a dark 

 reservoir, usually for a month or 6 weeks 

 (Stowell and Clancey, 1927; Wilson, 1952, 

 1960). 



ADDENDUM 



On the basis of the work of Saeki (1958) 

 and experiments recently performed at the 

 Cleveland Aquarium, Kelley (1963) has 

 described the parameters of an ideal sea- 

 water circulatory system. The relation of 

 volume of water to weight of animals 

 maintained in it is 100 gallons to 1 pound. 

 The water circulates completely once every 

 hour and passes through the filter at a 

 rate of 1 gallon per square foot per minute. 

 The filtrant consists of 2- to 5-mm. grains 

 of silica gravel (75 percent) and calcareous 

 gravel (25 percent) and there is 1 cubic 

 foot of it for each pound of animal. 



LITERATURE CITED 



Atkins, W. R. G. 



1931. Note on the condition of the water in a 

 marine aquarium. Journal of the Marine 

 Biological Association of the United King- 

 dom, vol. 17, No. 2, pp. 479-481. 



BoiiTius, .Tan. 



1960. Lethal action of mercuric chloride and 

 phenylmercuric acetate on fishes. Meddelel- 

 ser fra Danmarks Fiskeri- og Havunders0- 

 gelser, n.s., vol. 3, No. 4, pp. 93-115. 



Braker, William P. 



1961. Controlling salt water parasites. The 

 Aquarium (Norristown, Pa.), vol. 30, No. 1, 

 pp. 12-1.5. 



Breder. Charles M., .Jr. 



1931. On the organic equilibria in aquaria. 

 Copeia, 1931, No. 2, July 20, p. 66. Abstract 

 of paper. 



1934. Ecology of an oceanic fresh-water lake, 

 Andros Island, Bahamas, with special refer- 

 ence to its fishes. Zoologica (Ne-*^' York), 

 vol. 18, No. 3, pp. 57-88. 

 Breder, Charles M. Jr., and Thomas H. Howley. 



1931. The chemical control of closed circu- 

 lating systems of sea water in aquaria for 

 tropical marine fishes. Zoologica (New 

 York), vol. 9, No. 11, pp. 403-442. 



Breder, Charles M., Jr., and Homer W. Smith. 



1932. On the use of sodium bicarbonate and 

 calcium in the rectification of sea-water in 

 aquaria. Journal of the Marine Biological 

 Association of the United Kingdom, vol. 18, 

 No. 1, pp. 199-200. 



Brown, Eleanor M. 



1929. Notes on the hydrogen ion concentra- 

 tion, excess base, and carbon-dioxide pres- 



