THE AQUARIUM BUILDING 2Q 



vanized pipe is definitely toxic to aquatic organisms, 

 but after a period of time the insides of these pipes 

 become coated with an inactive deposit and the "raw 

 metal" is no longer exposed to the water. It is con- 

 ceivable, however, that water of some areas would not 

 produce a protective coating, and, further, the period 

 required to make the pipe safe under various condi- 

 tions is not known. It would thus appear that plastic is 

 the best choice even though it may be necessary to use 

 brass valves. 



DRAINS AND OVERFLOWS: The type of tank, 

 still-water or running-water, determines the nature of 

 its water supply and drain. Still-water tanks that are 

 drained or partly drained and refilled only occasion- 

 ally may not require individual supply and drains 

 whereas running-water tanks do require individual 

 service. 



A hose as a supply source and a suction type drain 

 service are satisfactory for small, still-water tanks. The 

 suction type drain is especially desirable since it may 

 be used to draw off insoluble materials which accumu- 

 late on the bottom of tanks. The system consists of a 

 steel drum equipped with a two-inch, gravity drain; 

 a garden hose connection on one top opening and a 

 vacuum cleaner suction hose on the other (Figure 4). 

 In operation the vacuum cleaner creates a vacuum in 

 the drum. The free end of the garden hose is then 

 used to clean the bottom of the tanks and to remove as 

 much water as desired. When the drum fills, it is 

 emptied by the gravity drain. A pump would also do 

 this job and for some situations might be preferred. 



