Product review (5 stars): Quaternary salt that keeps down microbe growth
This bacteriostat and algaecide contains Benzalkonium chloride aka dimethyl benzyl ammonium chloride. It's a quaternary ammonium compound and acts as a surfactant and something to kill or inhibit microbe growth.

Since warm standing water picks up bacteria and airborne algae, this keeps your humidifier clean and free of growth. Since we have a LOT of airborne algae (we are on two bays and there is a lot of marsh area) it's helpful to keep the humidifier clean of that green scum.

Benzalkonium chloride is the same ingredient that keeps eye, ear and nasal drops, nasal sprays, shampoos and lotions from growing bacteria.