D.I.Y airlift filter using Alfagrog

This is a D.I.Y airlift filter I built using the following items:-

• a plastic drinks bottle
• a short length of plastic pipe
• an air stone
• some Alfagrog filter media.

To build the filter...

The plastic pipe was drilled several times through the bottom inch or so, with a 3/16" drill (5 mm).
The plastic drinks bottle was cut to about 7" tall and the label was removed.
The pipe was held in the bottom of the bottle while the E25 Alfagrog was poured into the space around the outside pipe until the bottle was full..
Finally an air stone was inserted down the pipe to the bottom of the bottle. The filter was lowered into the aquarium and the air stone was connected to the air pump.

Note: this filter is a biological filter, it reduces harmful pollutants such as ammonia and nitrites from the water. It does not remove particles of matter from the water, a mechanical filter with sponges etc. is required to do this.

The filtration process...

As the air bubble rise up the pipe they carries along the water in the pipe, this water is replaced with water that passes through the holes in the base of the pipe, this water in turn is drawn down through the "Alfagrog" from the aquarium.
Beneficial bacteria will collect and multiply on the "Alfagrog" and as water flows over this material the water will be purified of any ammonia and nitrites it contains by these bacteria. The resultant nitrates produced by the bacteria will be absorbed by any plants present and can also be removed with water changes.

More information about Alfagrog can be found by visiting http://www.alfagrog.com/index.html