Fresh Air For Your Aquarium
Air pumps and their accessories are the most common and popular pieces of equipment in the aquarium hobby. They help to oxygenate your tank water so your fish can "breathe"! They can also be added to an aquarium (usually with an airstone) strictly for aesthetic purposes. Lastly, air pumps are also needed to operate some other types of aquarium equipment, like filters.
Applications For Use
Many times people add an air stone (powered by the air pump) to their aquarium simply to provide a beautiful flow of tiny bubbles. There are all different shapes and sizes of air stones, as well as ornaments that function with an air pump. (Remember the old opening and closing treasure chest in the Dr.'s office fish tank?)
Fish do require oxygen to breathe, though their oxygen supply is dissolved in their water. This often occurs at the surface of the water, where water agitation from a filter or air stone bubbles causes CO2 and O2 gas exchange. An air pump will power whatever aeration device you prefer (ceramic air stone, wooden air stone, "Bubble Wands," etc.).
Undergravel filters, sponge filters, and certain other filters use air pumps to function. The air from an air pump provides the aerobic bacteria with the oxygen they need to thrive as your biological filter.
Types Of Air Pumps
Some types of protein skimmers use an air stone to provide the bubbles/foam that all the protein and wastes attach to. The finer the bubbles the better.
This would be the type of air pump to get for any old air stone or decoration, as well as for powering sponge and undergravel filters. Silent Air by Penn Plax, Whisper by Tetra, and Rena Air by Aquarium Pharm. are 3 examples of a very basic air pump. Some of the larger pumps (for larger aquariums, obviously) have more than one output, so you can power two or three air stones or ornaments from one pump.
Types Of Airstones
These are general air pumps that run on batteries instead of plugging in. They are life-savers during power outages or when transporting fish.
An air stone made from these materials usually provide really small "micro" bubbles.
These air "stones" are often long and flexible, you can bend them in any shape to provide any bubble pattern you want.
Air Pump Accessories
A bubble disc provides an interesting 3D bubble effect.
This is the tubing you would use to connect the air pump (always outside the aquarium) to the air stone or other device inside the tank water. Some is ozone resistant for use on Ozone reactors.
Check valves should be used on every air pump installation. They prevent water from entering the pump outlets during power outages or when the pump is not plugged in. Back-siphoning water will damage air pumps and other equipment such as ozonizers.
Gang valves are used when more airlines are needed than are supplied directly from the pump itself. They are available in sets up to five, but can be expanded beyond that if necessary. The flow of air can then be individually adjusted from the gang valve to create the desired effect from each airstone, ornament, etc.
These items allow you to customize the flow of your air through various airline tubes.
Replacement Parts Kit:
Many air pumps feature their very own repair kit with replacement parts such as: diaphragm, air filter, rubber bushings, retainer plugs, valve flappers, and screws. Most include a special wrench to use when repairing.