For one part dosing, only one dosing pump is used to add nutrient to the mixing tank. When two-part dosing is selected then two dosing pumps will be used to add part A and part B stock solutions. In this case it is sometimes found the part A and part B do not dose at exactly the same rates (one tank empties quicker than the other).
There are a number of reasons why this may occur including different pipe arrangements, filters partly blocked, tanks or dosing valves mounted at different heights and even the fact that the two solutions may have different specific densities.
To compensate for this, you may adjust the two dose rates electronically by reducing either A or B dose rates below 100%. For example, if you set A at 100% and B at 95% then B will dose a little less than A each time that a dose is added to the tank. This is set by trial -and-error starting with both A and B at 100%.
(Always leave one at 100% and reduce the other)
In the advanced menu on the IntelliDose or the 'Functions' tab on IntelliGrow, select the units that you wish to use and then select one or two-part dosing.
To set manually
Calibrate the EC and pH sensors as described below
In “Configure” on the controller or 'Functions' in IntelliGrow, select one or two-part nutrient
In Dosing settings set the desired EC, pH and pH raise or lower
In Dosing settings set the EC dose time. This should be set so that each dose raises the EC by about 0.1mS/cm (1CF or 50ppm)
In Dosing set the pH dose time so that each dose alters the pH by about 0.1pH
In Dosing settings select either pH raise or pH lower. The most usual selection is pH lower (acid dosing) and if you are unsure then select this. If you find that the pH continually drifts down below 5.5pH then change this to pH raise and ensure that you have a dosing pump connected the pH raise output and to a stock tank containing pH raise (alkali)
In Dosing settings set the dose interval. This is the time taken for each dose to mix in and for the EC and pH readings to stabilise. For a small system, 2 or 3 minutes is typical. Larger systems may require 10 minutes or more. Note that dosing will not occur unless the reading has been below the setpoint continuously for this amount of time.