Performs the calculations for a dosage proportional sodium hypochlorite treated water flow measured by a counter with pulse output. If not available dosage counter is adjusted by four possible emulations flow, one, three, six or twelve day periods. Also in each can be selected from 5, 10, 15 and 20 cycles per hour. These options allow a good fit dosing. It also calculates the start and stop times of the dosficadora pump. This data can be entered into a timer or automatic. It presents a table of time and inactivation of Giardia virus for various concentrations of free residual chlorine at various temperatures and pH EPA.