What deviations during the calibration are usual and how are they connected to the temperature?
  
    It is difficult to give a precise answer without information about the sensor, particularly the age of the sensor. Good sensors have deviations in the range from 0.02 to 0.05 pH levels when calibrating. 
The input voltage differs for each sensor, as each sensor has its own individual properties. For the majority of our sensors, it is between -30 and +30 mV at pH 7. 
Both input voltages (pH 7 and pH 4) are important when assessing the quality of a sensor. The greater the difference between these two values, the better the sensor and the precision of the measurement and control. The differences should be over 140-150 mV. 
The temperature sensor should always be used during calibration. The pH level varies according to temperature, so that it is always best to measure the pH level with temperature compensation. The deviation is between 20 and 30 °C, 0.17 pH levels, and the relationship is nonlinear.
  
  
  
 
  What does the message INSTAB mean?
  
    The message INSTAB indicates: instable sensor voltage: the sensor tip is dirty, the electrolyte has leaked from the sensor, the sensor tip is damaged. 
Remedy: Clean the sensor head (see the respective instruction), put the sensor into the storage solution for 24 hours and repeat the calibration. If this does not work the sensor is defective and should be replaced.
  
  
  
 
  What does the message OFFSET mean?
  
    The message OFFSET indicates: The sensor voltage at pH 7.00 is outside the limit value, the sensor is too old, the cable is defective, no sensor is connected or the calibration has been performed with buffer 4 solution. 
Remedy: Check the sensor cable for any signs of damage and repeat the calibration. Take care to use the buffer solution correctly.  If this does not work, replace the sensor and calibrate again.
  
  
  
 
  What does DELTAV mean in the display?
  
    This message indicates that the potential difference per full pH unit is smaller than 30 mV. The pH sensor is either too old, defective or was accidentally calibrated twice with the same buffer solution. 
Remedy: Repeat the calibration and take care to use the buffer solution correctly. If this does not work, connect a new sensor and calibrate again.
  
  
  
 
  How often does the JBL pH/CO2 Control have to be calibrated?
  
    In the menu you have the chance to choose the interval before the next calibration reminder. The following calibration intervals are available: 
30 days 
45 days 
60 days
However it is highly recommended not to select the 60 days setting, since each pH sensor wears continuously and the measured values become subject to change. Thus the more often you carry out a calibration the more reliable are the measurement results.
  
  
  
 
  There is a fuzzy, white organism on the JBL pH Sensor. What can that be ?
  
    It is a harmless fungus which will disappear on its own after a while.
  
  
  
 
  Do I need a night switch-off when I use the JBL Proflora pH Control Touch or the JBL PROFLORA CO2 CONTROL?
  
    You need a separate soleniod valve (JBL ProFlora v002 or JBL PROFLORA CO2 VALVE) to control the CO2 supply. A further night switch-off for CO2 systems, controlled by a pH control unit is not needed, as the CO2 supply will not be turned on in the absence of CO2 consumption, or it will happen less frequently when CO2 degassing occurs at the water surface. That is why the control units do not need a timer