Water is an “eager” solvent for all manner of minerals, nutrients and foods.  Any circulated water such as fountain water can become a veritable “soup” of dissolved and suspended materials.  Such a “broth” is quite attractive to algae, bacteria and fungi.  Warmth, moisture, sunlight or darkness, nutrients and food - all of the ingredients necessary for biological growth are present in a fountain.  The object of a biological control program is to always make fountain water unattractive for biological growth.  The challenge is to inhibit visible growth, not kill growth which has already occurred.   Killing algae and slimes after they form is a lost cause.

Biological Fouling
Algae don’t ask for much in life. They are simple plants which contain chlorophyll and are usually green.  They thrive on sunlight, air, warmth and water “laced” with nutrients (fertilizers) - primarily nitrogen and phosphorous.  Bacteria and fungi eat almost any organic material which finds its way into a fountain. They can live quite successfully on leaves, pollens and dusts - even dead algae.  This means inhibiting algal growth is doubly important.

QUAT is a surface active agent, a “surfactant” (detergent).  It reduces the ability of algae, bacteria and fungi to exclude outside materials from entering the cell and interior materials from leaking out.  The cell’s metabolism is disrupted and it dies.