24 



H. J. THOMAS 



^; 



lid 



rubber sealing 

 qasket 



cover with 

 chimney 



rhumb screw 



cover 



attachment 



Figure 3.— Carrying tank for live material. 



TEMPERATURE CONTROL 



For general purposes the aquarium wa- 

 ter is allowed to take up its natural tem- 

 perature. In hot weather, however, the 

 maximum temperature is held to about 14° 

 C, whilst in cold weather a minimum of 

 around 6° C. is maintained. 



Heating or cooling under thermostatic 

 control is applied in the service tank (fig. 

 1) which is effectively that section of the 

 reservoir tank from which sea water is im- 

 mediately drawn to supply the aquarium 

 system. The cooling system is rated to 

 maintain a maximum temperature of 12° 

 C. The heating system is capable of hold- 

 ing 8° C. minimum temperature through- 

 out the aquarium. This allows for the 

 aquarium being run throughout the year 

 at the appropriate seasonal temperature 

 normal to the open sea around Scotland. 

 Alternatively, most of the year, the aqua- 

 rium can be run at any desired normal 

 temperature between 5° and 16° C. In 

 extremes of climate, such a desired tem- 



perature can be held over a part of the 

 aquarium system with the remainder off 

 circulation. 



SPECIAL FEATURES 



Temperature control is the most fre- 

 quent requirement in an experimental 

 aquarium. In addition to the general con- 

 trol outlined above, two tanks, each of 700 

 gallons' capacity, which are normally in- 

 corporated in the general circulation, can 

 be isolated, either singly or together, into 

 a separate unit controllable as to tempera- 

 ture within the range 4°-20° C. (figs. 4 

 and 5). The system alternatively pro- 

 vides an offtake of temperature-controlled 

 sea water to the circulation bench for use 

 with portable tanks. The relevant capac- 

 ities and ratings for the temperature- 

 controlled system are as follows: 



Volume of twin display tanks 



(700 gallons each) 1,400 gallons 



Volume of header heat-exchanger 



tank 100 gallons 



Circulation pump rated capacity 1,000 gallons 



per hour 



Refrigerator rated capacity 27,000 Btu 



Heater capacity 6 kilowatts 



Experimental procedures frequently de- 

 mand a sea-water tank controlled to a tem- 

 perature below room temperature. A 

 small unit (preferably transportable) 

 used for cooling a number of small tanks 

 to different preset temperatures is shown 

 in figure 6. A reservoir of brine, or anti- 

 freeze solution, is maintained at a low 

 temperature, and this is pumped through 

 glass cooling coils immersed in the water 

 of the experimental tank(s). The opera- 

 tion of the pump is thermostatically con- 

 trolled. The number of tanks which can 

 be coupled to this system depends on the 

 regulated temperatures to be maintained. 

 It can be materially increased by insu- 

 lating the experimental tanks against heat 

 loss. 



