Industrial CH240 pH Digital Controller


CHEMTROL® 240 is a microprocessor-based digital controller designed to maintain the pH level in water treatment applications. The bright LCD display shows pH readings, calibration adjustments and alarm limits.


  • Easy to install, Simple to use
  • All Functions on Front Panel
  • pH control
  • Overfeed Safety Timer
  • Adjustable Set-point
  • Adjustable Alarms
  • Out-of-range alarms
  • Proportional Feed
  • Waterproof Cabinet
  • 5-year Electronics Warranty

The five LED lights indicate the operating mode (OFF, Manual or Auto), feed status, out-of-range alarms and overfeed alarms. The front panel controls include setpoint, calibration, low and high alarm limits, safety timer limit and proportional feed adjustment.
Feed control is either ON/OFF or Proportional. The Proportional Feed feature is particularly useful to avoid overfeeding in small bodies of water. It reduces the feed cycle time progressively as the sensor reading gets closer to the set-point.


pH CONTROL Adjustable from 0.0 to 14.0
pH SENSOR Glass electrode with 3 m cable
READOUTS pH (2 digits) LEDs
FEED MODE Manual, automatic, proportional
ADJUSTMENTS Set-point, calibration, limits, feed rate
INDICATORS LEDs for feed mode, feed status, alarms
SAFETY Audio, visual and remote alarms
Out-of-range limits and overfeed safety timers
CABINET Polystyrene 22 x 18 x 10 cm
ELECTRICAL 230V or 24 VAC (specify)
PLUMBING PVC tees for 1-1/2″ or 2″ line
WARRANTY 5 years on electronic module
1 year on all other parts


  1. CONTROLLER – Connect the controller to 230V output of the Timer in parallel to the recirculation pump.  This will prevent accidental feeding of chemicals when the pump is not running. Make sure to follow the electrical code.
  2. SENSOR – Install the pH sensor on the recirculation line or on the optional bypass line.  The sensor can be mounted directly on the main recirculation line with a 2″ PVC tee, as shown on the schematic.  For recirculation lines over 2″ in diameter lines, the sensor should be mounted on a 1/2″ bypass line.
  3. CHEMICAL FEEDER – Connect the chemical feeder to 230V controller output, according to the manufacturer’s instructions, making sure to inject the chemicals downstream of the sensor. For a bromine or chlorine erosion feeder, install a corrosion-resistant solenoid valve on the intake line of the feeder. The controller is compatible with most ozonators and electrolytic generators.


The CHEMTROL® 240 pH Digital Controller automatically maintains both the sanitizer pH (oxidation-reduction potential or Redox) level.

All operating functions are clearly labeled and accessible from the front panel, with many safety and easy-reset features not found on other controllers:

  • pH calibration from 4 to 10,
  • pH setpoint from 4 to 10,
  • feed modes: off, manual, automatic,
  • proportional control bandwidth from 0 to 100% of the setpoint,
  • pH high and low alarms from 4 to 10,
  • overfeed safety timer from 0 to 99 minutes.

To select a function, simply press pH and then the desired function.  The display shows the current function value.  Use the UP or DOWN arrows to adjust to the desired value.


The standard factory-set pH control level is 7.5  based on WORLD HEALTH ORGANIZATION (WHO) values for prevention of germs and bacteria.

To change the control level, press pH and then SETPOINT. Use the UP or DOWN arrows to adjust the pH setpoints. To save the new setpoint value and exit, press SETPOINT again.

The controller then automatically activates the chemical feeder for sanitizer feed, as required to maintain the set pH levels – regardless of fluctuations in bather load, contamination and weather. Like a thermostat maintaining a constant temperature, it prevents overfeeding or underfeeding, both of which are detrimental to good water quality.


When there is an alarm condition, the corresponding display flashes the alarm value:

  • pH out-of-range,
  • pH overfeed.

The display stops flashing when the condition is corrected. To reset the overfeed timers, turn the feed mode to off and then back to Manual or Auto.


The ideal values are set as default values.  They can be adjusted by the operator at any time.  To reset all factory default values, press pH for 5 seconds.