Written by Anthony Olszewski
P.O. Box 3362
Jersey City, NJ 07302
22. october 1997
I use perlite for aquarium filtration. Perlite is a white, light material that is often used to mix with potting soil. Perlite has a very large surface. It offers great opportunities for both mechanical and biological filtration.
There is another advantage to freshwater systems: when perlite needs to be replaced, it can be immediately reused as soil for house and garden plants.
As a side note, when you change the water, the water from an aquarium is great as a fertilizer for plants.
Perlite is available in three grain sizes: fine, medium and coarse. The fine is a powder with the appearance of flour. Fine perlite can be used instead of diatomaceous earth in a diatomaceous earth filter. Medium grain size is two or three times the size of sand grain. Coarse grain size is approximately the same size as gravel. The coarse grain is what is usually used for potted plants.
I have set up a container that uses medium perlite in the aquarium filter. With relatively fine perlite, it was necessary to squeeze the material in between the sponges. It was easy, because the filter is constructed with three chambers for this reason. Spagnum is often used in the middle chamber.
The next morning, the water was crystal clear. I put a dozen Blind Hollow Fish in the container the following day. The fish are extremely active and do well. Their appetize is phenomenal. The water remains crystal clear.
To give perlite a thorough test, I then started a 150 liter aquarium with Oscar Ciklider. I continued to use the big filter with Oscar Ciklider. I used a smaller one in the Black Molly container. Now I use coarse perlite in the middle of the filter insert. Medium grain size continues to operate on the top and bottom of the filter insert with sponges to retain perlite in the filter insert.