SEA-WATER SUPPLY SYSTEM 



IN A SHELLFISH-CULTURE LABORATORY 



By P. R. Wainc 



Ministry of Agriculture, Fisheries, and Food, Conway, Wales 



Abstract.— The sea- water supply system of a set of laboratories devoted to the culture 

 of bivalve mollusks is described. The water is distributed from roof tanks to a tank 

 room where it is heated and enriched with phytoplankton, and to the hatchery where 

 it is filtered and sterilized. The equipment used for heating, filtering, and auto- 

 matically enriching with algal cultures is discussed. 



The sea-water system described in this 

 paper is used in a hiboratory engaged in 

 investigations on the cuUnre of larval and 

 adult bivalve mollusks. It is built on a 

 site adjacent to a set of concrete tanks con- 

 structed 50 years ago for mussel purifica- 

 tion, and the pumping facilities of these 

 tanks are also used to deliver sea water 

 into the main laboratory storage tank. 

 The site is on the estuary of the river Con- 

 way, and suitable-salinity water is obtain- 

 able only for a few hours at high tide. 

 Apart from this, some storage is desirable 

 to reduce the silt content of the water 

 which is liable to be high during rough 

 weather. 



The use of metals has been avoided as 

 far as possible in the construction of this 

 system. The largest amount of metal is 

 the iron main through which the water is 

 first pumped. From the results obtained, 

 this seems to be quite harmless, but the 

 continual addition of rust to the water is 

 a nuisance at times. 



GENERAL LAYOUT 



The water is pumped up from the estu- 

 ary by a centrifugal pump with cast-iron 

 body and impeller driven by a 30-horse- 

 pow^er electric induction motor and is de- 

 livered (for laboratory purposes) through 



6-inch cast-iron pipes into a 20,000-gallon 

 reinforced-concrete tank at 40,000 gallons 

 per hour. From the main outside storage 

 tank the water is pumped as required 

 through a 2-inch polythene pipe into a set 

 of three interconnected 100-gallon fiber- 

 glass tanks in the roof of the laboratory 

 block. Fiberglass tanks were chosen be- 

 cause of their lightness and freedom from 

 corrosion, and after tests had shown that 

 oyster larvae could be satisfactorily cul- 

 tured in them. The pump, which is close 

 to the wall of the main storage tank, is a 

 2-inch pump (Mono Pumps Ltd., London) 

 with a stainless-steel rotor and a rubber 

 stator and is sited below^ the level of the 

 water in the tank. This is important in 

 a pump under automatic control, since it 

 eliminates trouble due either to failure of 

 the pump to prime or, if a foot valve is 

 used, to leakage due to dirt or organisms 

 growing on the valve. The pump is con- 

 trolled by a float switch (Stuart Turner 

 Ltd., Henley-on-Thames) in the labora- 

 tory roof tanks which are thus auto- 

 matically kept nearly full of water. As 

 there is no foot valve on the pump, the 

 pipe empties to the level of the water in 

 the storage tank wdien the pump stops, 

 and this prevents the growth of sedentary 

 organisms in the pipe. 



712-029 O - 64 - 11 



155 



