THE AQUARIUM BUDLDING
25
Water
LEVEL
OVERFLOW
WATER —
IWIInWIIIIIh
•OVERFLOW
.LARGER PfPE PLACED
OVER OVERFLOW PIPE
CAUSES WATER TO RISE
FROM BOTTOM OF TANK
y-^UBBER 6T0PPE«
/ /-ORAIM
5. Sectional view of a gravity drain and overflow for
fish tanks.
Compressed Air
An aquarium building should have a compressed air supply throughout. Each tank should have
a valve and two or more should be available for larger
tanks. Since this air supply is of fairly low pressure,
at least three-quarter inch galvanized steel pipe
equipped with needle valves is recommended. Other
t^'pes of valves do not permit the degree of control of
air flow that is desirable. The compressor should be a
high-volume, low-pressure type. The need is for a
constant air supply, hence a tank equipped \\dth a
pressure swdtch is not desirable. It is more satisfactory
to permit the compressor to run continuously. All of
these requirements are best met by an oilless, rotary
pump. Most conventional piston pumps have a high
pressure, low volume characteristic and are not satisfactory (see also section on Aeration). For a small
number of tanks one may use any one of a number of
small diaphram or piston pumps designed for aquarium use.