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.

I have found that perlite is great for both biological and mechanical filtration. It really cleans the water.

I have found that perlite is great for both biological and mechanical filtration. It really cleans the water.

Before putting Perlite in the filter, put it in a net under the tap. If you don’t do that, the filter will first produce a milky effect. It does not appear to bother the fish and the filter will quickly remove the “clouds” of perlite dust. As it’s easy to avoid, you might as well rinse the perlite with tap water.

Another great application of perlite can be in pond filters. Used materials can be an excellent way to improve the soil of the surrounding garden.

For more information about these and many other uses of
Perlite please call or contact us or our distributors

Like other siliceous volcanic rocks, some Perlite products contain crystalline silica, which has been linked to the lung disease silicosis. The amount of this substance in Perlite is often less than 1 percent by weight, which is far less than the 60 percent by weight contained in DE./ Kieselguhr (For more information on DE / Kieselguhr and silicosis, see P/SN, Oct. 1, p. 112.) This stark difference could lead one to assume that Perlite poses less of a health threat – and indeed, that was the result of a 1994 study of Perlite industrial and mining workers conducted by Dr. Hans Weill of Tulane University in New Orleans. In his report, Dr. Weill noted that there wasn’t any evidence to indicate an increased incidence of silicosis among these workers than there was among the general public. What’s more, the American Conference of Governmental Industrial Hygienists only classifies Perlite as a “nuisance dust”. The group of health-care experts does, however, advise Perlite users to exercise common sense when using the product to avoid skin or eye irritation and to avoid directly inhaling it. – A.B.E.