Harmopool Duo Manual page 10

 During 2 minutes, the following happens:
o If the PH value is much higher than the setpoint (target), the metering pump
always rotates
o If the PH value comes closer to the setpoint value, the metering pump goes on
and off. The closer PH value you get to the set point value, the less the pump is
running
o The salt electrolysis device will allow salt electrolysis to function for 2 minutes,
if the Redox is lower than the setpoint. After two minutes, salt electrolysis and
pH dosage will stop, and pH and Redox will be measured again. This circle
repeats continuously
3. PH + or PH-
Press the lower button. The setting "PH + or PH-" is now checked. Press the center button to
activate this setting. If the character appears, press the middle button again. Now you have the
supply of PH-settled.
PH- must be adjusted when using liquid chlorine. Liquid chlorine already contains PH + which
is always added as a stabilizer.
PH- must be set using salt electrolysis. In the production of chlorine by the salt electrolysis
device, PH + (NaOH) is formed as by-product.
It is not possible to use PH + and PH- at the same time : one of both needs to be selected.