AQUARIUM OF MARINE LABORATORY, ABERDEEN 



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Figure 4. — Circulation system of the temperature-regulated experimental tanks : B, experimental 

 bench ; C, cooling coils ; E, immersion heater : F, filter ; H, header and temperature-control tank ; 

 P, circulation pump ; Ti, experimental tank, depicted on general circulation ; T2, experimental 

 tank, depicted on temperature-control circulation. 



ISOLATED TANKS 



Experiments frequently involve dis- 

 eased fish or techniques which may con- 

 taminate the sea ^Yater. Such experiments 

 must be undertaken in such a way that 

 there can be no risk to the general aquar- 

 ium circulation, namely, in a separate sea- 

 water tank system. The unit described 

 below has proved most serviceable and 

 consequently is preferred even where the 

 procedures involved are no bar to the use 

 of the main aquarium. The system is sim- 

 ple and relatively cheap to construct. 



The unit consists of two reinforced-con- 

 crete tanks 12 by 6 by 6 feet, each capable 

 of subdivision by a sectional teak partition 

 (fig. 7) . An air lift maintains circulation 



of the sea water over a sand filter, whence 

 it gravitates back to the bottom of the ex- 

 perimental tank. The base of the filter 

 is at the level of the top of the tank so that 

 the lift is a minimum. Aeration is pro- 

 vided using two Doulton filter candles 

 ( Doulton & Co. Ltd. ) , grade KF, as atom- 

 izers. The constructional details follow 

 those outlined for the main aquarium. 

 The tanks and filters are imhoused and 

 fitted with removable covers. 



GENERAL 



It frequently happens that when an 

 aquarium is in design there are a number 

 of research projects immediately envis- 

 aged. Nevertheless it is essential that the 



