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SKU HI9935-1 Categories ,

Industrial grade pH Controller with TDS control and Proportional Fertilizer Dosing - HI9935-1

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HI9935 is a wall mounted Industrial grade pH Controller that measures and controls pH and TDS  for fertilizer solution dosage in hydroponics.The relays are activated when the pH exceeds the set point or TDS falls below the desired value. Two pumps or electrovalves can be wired directly to the controller and be powered through the terminals.

  • Fail Safe Alarm System protects against problems caused by power supply failure or signal interruption.
  • Readings are automatically compensated for the effects of temperature for more accurate results.
  • See the controller’s status, even from a distance, by observing the dosage or alarm LED’s.

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Triple Contact Alarm System

When activated, the alarm contacts will open or close, triggering the mechanism of your choice, whether a buzzer, light or any other electrical device. The alarm is activated when the measurements exceed the setpoint by a user-selectable margin from 50 to 450 mg/L (ppm).

Simple Probe Installation

HI9935 operates with the optional Hanna 4-ring probes to provide a linear and repeatable measurement. The conductivity/TDS probe can be installed quickly and easily. Simply plug the DIN connector into the socket and tighten the retainer ring. The TDS probe incorporates a temperature sensor and the controllers will automatically compensate for the temperature effect. Similarly, the pH electrode can be installed quickly and easily. Simply plug the universal BNC connector into the socket and twist it into a secured position.

Matching Pin

A matching pin/ground probe can be connected to the appropriate terminals to extend electrode life and eliminate interference.

Fail Safe Alarm System

Hanna’s exclusive Fail Safe Alarm System protects against problems caused by power supply failure or signal interruption, which are typical risks in industrial environments. An alarm condition is indicated by a red LED, located directly on the front panel of the controller.

Proportional Control

With proportional control, you can fine tune your treatment plant and minimize the use of chemicals. The proportional settings can be fine tuned through two conveniently positioned dials on the front panel. Independent proportional settings for pH and TDS can be adjusted from 0 to 90 seconds, 0 to 2.0 for pH and 0 to 400 mg/L (ppm) for TDS.

Durable Construction

This controller is housed in a rugged, modular, fiber-reinforced ABS housing.




0.0 to 14.0 pH


0.01 % pH


±0.02 pH



0.00 to 1999 ppm (mg/L)


1 ppm (mg/L)

Accuracy (@20°C/68°F)

±2% F. S

Typical EMC Deviation

±2 % full scale (EC and TDS) / ±0.5 °C


Through “OFFSET” and “SLOPE” trimmers for pH, and “ZERO CAL” and “SLOPE CAL” for TDS


From 4.0 to 7.0 pH and 900 to 1800 ppm (mg/L


adjustable, typically from 5 to approximately 30 minutes

Proportional Control 

Two independent controls: pH from 0.0 to 2.0 and TDS from 0.0 to 400 ppm (mg/L) with two separate time cycles from 0 to 90 seconds

Alarm Contact

Terminals can be configured as normally open or normally closed (isolated output Max. 2A, Max. 240V, resistive load, 1,000,000 strokes). The alarm is activated if pH falls below the setpoint by the userselectable interval (0 to 2 pH),or TDS exceeds the setpoint by more than the user-selectable interval (0 to 400 ppm) or due to overdosage

TDS Ratio

0.65 ppm (mg/L) = 1 µS/cm

Input Impedance

10¹² Ohm


Any combination pH electrode with a universal BNC connector and Hanna TDS 4-ring potentiometric probe with built-in temperature sensor and DIN connector (optional)

Dosing Terminals

Two sets of independent terminals (115 to 240V, Max. 2A, 1,000,000 strokes) are activated whenever pH exceeds the pH setpoint and for the TDS falls below the TDS setpoint

Power Supply

220/240V or 110/115V at 50/60Hz


0 to 50°C (32 to 122°F); RH max 95% non-condensing

Enclosure/ Case Material

Fiber-reinforced, self-extinguishing ABS


181 x 221 x 142mm (7.1 x 8.7 x 5.6″)


1.6 Kg (3.5 lb.)

Additional Informations

Additional information





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