For established populations in recirculating and once-through cooling water systems, apply at 0.3 to 3.0 ppm of the active ingredient endothall for 6 to 144 hr of exposure. These concentrations are equivalent to 9.1 to 91 L per 38,000,000 L water (2.4 to 24 gal of EVAC per 1,000,000 gal of water).
The higher rates of application and exposure times are required for heavy populations of fouling mollusks and/or with cooler water temperatures (less than 70 EF or 21 EC).
Laboratory studies show that efficacy is dependent on rate of application and time of exposure. For example, treatments of 2.3 ppm for 6 to 7 hr were equivalent to those at 5 ppm for 2 hr.
For byssal thread detachment, use 0.5 mg L-1 (Piccirillo, Dionne, and Sandberg 1997).