Freshwater

Figure 6-2:
An air pump
adds
bubbles to
the water,
helping gas
exchange at
the surface.
Air pumps
Chapter 6: Equipment and Other Technical Stuff
An air pump is kind of a jack-of-all-trades. They can power filters, airstones,
and several types of plastic decorations. Air pumps are available in both
vibrator and piston models. When added to an undergravel filter, a pump
drives air though the airstone in the uplift tubes via tubing. The air is then
broken up into small bubbles as it passes through an airstone and up the
tube. See Figure 6-2 for a typical air pump.
An air pump should always sit above the midpoint level of the aquarium to
avoid water backflow (which can ruin your pump) if electrical power is lost.
For example, if your aquarium is 12 inches tall, the pump should sit higher
than 6 inches measured from the bottom of the tank.
However the easy solution to this problem is to buy a checkvalve. The checkvalve
is a small plastic cylindrical object that allows water or air to flow in
only one direction, so that any backflow of water will not damage your pump.
The check valve is added to the air-line tubing.
Air pumps come in a variety of different sizes to suit almost any filter. (All filters
are driven either by an air pump or an electric motor.)
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