Tests of various potassium salts show that adults are killed rapidly, with median lethal concentrations LC50's at 80 to 313 mg L-1 (Fisher et al. 1991). A concentration of 50 mg L-1 prevents settlement (Fisher, Fisher, and Polizotto 1993). The following tabulation lists the toxicities of potassium salts.
To prevent primary settlement, use 30 ppm on a continuous basis.
At water temperatures above 15 ºC, 40 ppm for 2 weeks gives control.
At water temperatures above 15 ºC, 100 ppm gives 100 percent mortality in 48 hr.