How an air lifter works
An air lift is a tube into which air is blown at the bottom. Foam filters often work according to this principle.
The air bubbles lower the density of the fluid in the pipe. This reduces the static pressure at the inlet of the pipe. The pressure at the entrance is therefore below the pressure of the environment. Water flows from the aquarium into the pipe to equalize the pressure. Water would continue to flow until the pressure of the water column in the pipe at the entrance equals the ambient pressure. However, because water is constantly running back into the aquarium at the top, there is always a negative pressure and the water is constantly flowing.
The performance of a pump based on this principle is greater, the longer the vertical pipe is under water and the less it protrudes above the surface. In addition, the flow rate depends on the performance of the pump.
Air lifters can make annoying noises if the pump vibrations are too loud or if the air bubbles are bubbling and bursting loudly.
The vibrations of the pump usually become disturbingly loud when the pump or the air hose hit a resonance surface. There are various measures to dampen these vibrations.
The air bubbles develop disturbing noises for the following reasons:
- Air jacks are noisy if too much air is pumped through.
- The bigger the air bubbles, the louder they burst.
- The deeper the water outlet is in the water, the louder the bubbles burst.
If too much air is pumped through and there are no adjustment options on the pump, small Gardena taps can be installed to adjust the air flow. In the aquarium trade there are also simple taps with which air or water can be regulated.
It is possible that the noise is not coming from the bursting air bubbles, but also from the air pump, whose vibrations are transmitted down the hose. In this case, the following procedure helps:
- Disconnect the air hose in the middle.
- In a large jar with a lid, thread the tubing through the lid to the bottom of the jar.
- Fill the glass with filter floss.
- Attach the second section of hose above the filter floss.
- Place the lid on the jar and seal tightly.
It is easier to put foam on the water outlet. This even results in additional settlement area for bacteria.