One piece of aquarium equipment that has seen the biggest decline in demand since the “golden age” of the 60-70’s is the air pump. Nearly all current air pumps use a rubber diaphragm and electromagnet swing arm to produce the movement of air. Older models used to use electric motors and a piston system, but these were noisy and required too much power and maintenance. Today’s air pumps have better types of plastic flappers and diaphragms and will generally perform for years between required maintenance. Most also require less than 10W of power to produce larger amounts of air.
Air pumps can be used to generate an air/water flow through the lift tubes of under-gravel filters, but usually are used with air stones or bubble bars to produce a stream of air bubbles in the aquarium. While a great many are used for esthetic reasons, using an air stone does create currents in the water to “push” water from the lower levels to the surface and help turn over the volume of water. This, in addition to the bubbles themselves, increases the contact with the atmosphere and ensures proper oxygen saturation levels for the health of the fish. The recent addition of LED’s to the bubble bars allows the hobbyist to create a focal point that is an almost hypnotic stream of color and movement. Plus, there are many species of fish that like to “play” in the bubbles and swim against the water currents they create.
Unless you can place your air pump above the water level of the aquarium, you will want to do one of two things to protect the air pump from accidentally creating a “back siphon” when the power goes off. You can use a one way check valve to stop any water from flowing into the air pump, or use a gang valve with one extra outlet slightly opened to allow some air to bleed off and to prevent a siphon from starting. Air stones usually require replacement after 6-9 months, or else a good soaking in vinegar to remove hard water deposits and algae build-up. As mentioned earlier, today’s air pumps will not need repair for several years, but most do offer replacement diaphragms, flappers and pivot arms to make them as good as new. Most air pump models have one or two outlets, and some come with a rheostat controller to modify the amount of air they produce. You may see a PSI rating for the pumps, the higher the number, the deeper they can drive air into the water. Some pumps are designed as volume pumps, while others are designed for higher pressure situations. Most volume pumps are not designed for the living or bed room, but for use in a dedicated fish room or basement. The Airpod is unique in its ability to switch over to an internal battery if the main power goes out, while the Silent Air B11 Battery pump is one you can manually run with D cell batteries. Good to have if you are in an area that loses power often.