252 U. S. BUREAU OP FISHEBIES 



City waters that are treated with chlorine are not suitable for 

 aquarium purposes. The United States Bureau of Fisheries has 

 proposed a method of treatment for removal of chlorine from city 

 water for use in aquariums. (See Aj^pendix B.) 



The distribution of water throughout the building must be ar- 

 ranged so that it can be supplied to exhibition tanks in considerable 

 volume if necessary. Some species of fishes require a stronger flow 

 than others, and all crowded tanks need it. The supply to each tank 

 can be reduced easily by means of valves to suit the demand and 

 might not be sufficient if the distributing lines of pipe were too 

 small. 



The reservoir should be constructed with two or more compart- 

 ments to facilitate periodical cleaning and to give the body of water 

 not in use a period of rest, such treatment having a clarifying effect. 

 All equipment tending to facilitate the distribution of stored water 

 and to preserve its purity is desirable, as its vitiation, even in small 

 degree, may result in serious losses of animal life. The living occu- 

 pants of the aquarium have no choice but to remain in the tanks 

 where they are placed. Lack of food can be endured long, but the 

 impairment of their natural element is immediately fatal, whether 

 from actual fouling or mere lack of oxygen. They may long sur- 

 vive overcrowding if the supply of water is abundant. The loss of 

 many marine exhibits may prove less expensive to an inland aquarium 

 than the restoration of a damaged water supply. 



There need be little deterioration of stored water if it is managed 

 properly; circulation, filtration, and periods of rest for the precipita- 

 tion of sediment will keep it in fair condition for a long time. 

 Additions to the supply will be necessary occasionally to replace 

 losses from leakage and evaporation. Even after years of use the 

 increase in salinity from evaporation is negligible, and this can be 

 corrected by the addition of fresh water. Aeration is automatic, as 

 the surface of the water is exposed to air both in the reservoir and 

 exhibition tanks, and the water is aerated further in falling from the 

 various levels to which it is i)umped. 



Stored sea water should be protected against discoloration from 

 iron rust, but this is not difficult if the pumps and piping are made 

 of nonrusting materials. Its action on iron pumps and piping is 

 destructive, and galvanizing affords only temporary protection. 



The care of the water supply of any large aquarium is an ever- 

 present responsibility that must be kept in mind by each employee 

 of the institution during his hours of duty. While many of the 

 operations relative to it are accomplished by mechanical means, the 

 feeling of personal responsibility can not be relaxed. 



Pure water being the lifeblood of the aquarium organism, the 

 mechanical means for securing its circulation and preservation are 

 next in importance. The circulating }nnnp, piping, and filters may 

 be compared to heart, arteries, and lungs. The mechanical depart- 

 ment of the institution is responsible for the continuous flow of 

 water, its temperature, aeration, and Alteration. A considerable 

 amount of machinery is necessary in a large aquarium, the principal 

 features of which are pump, air compressor, filter, refrigerating 

 machine, and water heater. In most larg<e aquariums the pumping 

 machinery is installed in duplicate as a safeguard against accidents, 



