HI96710 pH, Free Chlorine, and Total Chlorine Portable Photometer

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HI96710 pH, Free Chlorine, and Total Chlorine Portable Photometer

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The HI96710 pH, Free Chlorine, and Total Chlorine Portable Photometer combines accuracy and ease of use in an ergonomic, portable design. A user can accurately determine the pH, free chlorine, and total chlorine concentration of water samples using ready made reagents. The HI96710 offers many advanced features including the exclusive CAL Check function used for performance verification and calibration of the meter.

CAL Check Validation and Calibration

Built-in Timer

Automatic Shut Off


The HI96710 portable photometer is for the measurement of pH, free chlorine, and total chlorine. Hanna's portable photometers feature an advanced optical system; the combination of a special tungsten lamp, a narrow band interference filter, and silicon photodetector ensure accurate photometric readings every time. The Hanna exclusive CAL Check feature utilizes ready-made, NIST traceable standards to verify both meter validation and calibration. The exclusive cuvette locking system ensures that the cuvette is inserted into the measurement cell in the same position every time to maintain a consistent path length.


Features at-a-glance

CAL Check™ - Allows for performance verification and calibration of the meter using NIST traceable standards.

GLP - Review of the last calibration date.

Auto-shut off - Automatic shut off after 10 minutes of non-use when the meter is in measurement mode. Prevents wastage of batteries in the event the meter is accidentally left on.

Battery status indicator - Indicates the amount of battery life left.

Built-in timer - Display of time remaining before a measurement is taken. Ensures that all readings are taken at the appropriate reaction intervals for the test being performed.

Error messages - Messages on display alerting to problems including no cap, high zero, and standard too low.

Cooling lamp indicator - To maintain the desirable wavelength to be used for absorbance, it is necessary to ensure components are not overheated from the heat generated by the tungsten lamp. Each photometer is designed to allow a minimal amount of time for components to cool. The cooling lamp indicator is displayed prior to a reading being taken.

Units of measure - Appropriate unit of measure is displayed along with reading.


optical system

Three critical parameters that can be tested to ensure good water quality are pH, free chlorine, and total chlorine. Chlorine is one of the most commonly used disinfectants for drinking water, wastewater, and water used for pools and spas. It can be added to in various forms including calcium hypochlorite, sodium hypochlorite, or in some instances, chlorine gas. When added to water, chlorine creates hypochlorous acid (HOCl) which dissociates into hypochlorite ion (OCl-).

HOCl ↔ H+ + OCl- hypochlorous acid ↔ hydrogen ion + hypochlorite ion

HOCl is the form of chlorine that acts as a stronger disinfectant as compared to OCl-. To ensure the added chlorine is effective at sanitizing, the pH of the water must be taken into account. Around pH 7.5, HOCl and OCl- are present in relatively equal amounts. Below pH 7.5, the equilibrium shifts to favor HOCl; above pH 7.5, the equilibrium shifts to favor OCl-. Depending on the application, addition of chlorine is effective when added to water with a neutral or slightly acidic pH value.

When chlorine is first added to water, it is available as free chlorine. The measurement of free chlorine signifies the amount available for disinfection. Once chlorine begins to sanitize bacteria and pathogens present in the water, it becomes combined chlorine; combined chlorine is no longer available to act as a disinfectant. The measurement of total chlorine signifies the amount of free chlorine and combined chlorine. With both free and total chlorine measurements, a drinking water operator or pool owner can determine if there is enough chlorine available for disinfection.

The HI96710 offers multiple methods within one meter. pH determination uses the phenol red method while free and total chlorine determination uses an adaptation of the EPA method 330.5. The reagents are in powder and liquid form depending on the parameter being tested.

When the appropriate reagent is added to the sample, it will display a color change; the greater the concentration, the deeper the color. The associated color change is then colorimetrically analyzed according to the Beer-Lambert Law. This principle states that light is absorbed by a complementary color, and the emitted radiation is dependent upon concentration. For determination of pH and free and total chlorine, a narrow band interference filter at 525 nm (green) allows only green light to be detected by the silicon photodetector and omits all other visible light emitted from the tungsten lamp. As the change in color of the reacted sample increases, absorbance of the specific wavelength of light also increases, while transmittance decreases.


The HI96710 is available as a kit which includes:

  • Portable Photometer
  • Sample cuvettes (2)
  • Caps
  • CAL Check™ standards with certificate
  • Cuvette cleaning cloth
  • Rugged carrying case
    • Carrying case has thermoformed insert for meter and accessories
*Reagents ordered separately
cal check standards

CAL Check™ standards with certificate

The CAL Check standards are used for calibration and performance verification of photometers with the CAL Check function. Individual sets of CAL Check standards are available for each parameter found in the HI96710:

  • pH: HI96710-11
  • Free Chlorine: HI96701-11
  • Total Chlorine: HI96711-11

Supplied with Certificate of Analysis
  • Lot number
  • Expiration date
  • Standard value @ 25 °C
  • Reference meter NIST traceable
Provided storage containers
  • Light tight
  • Protects from accidental breakage
photometer steps



Range pH (P1): 6.5 to 8.5 pH; Free & Total Chlorine (P2 & P3): 0.00 to 5.00 mg/L (ppm)
Resolution pH (P1): 0.1 pH; Free & Total Chlorine (P2 & P3): 0.01 mg/L under 3.50 mg/L; 0.10 mg/L above 3.50 mg/L
Accuracy @ 25°C (77°F) pH (P1): ±0.1 pH; Free & Total Chlorine (P2 & P3): ±0.03 mg/L (ppm) ±3% of reading
Light Source tungsten lamp
Light Detector silicon photocell with narrow band interference filter @ 525 nm
Method pH (P1): phenol red method; Free & Total Chlorine (P2 & P3): adaptation of the USEPA method 330.5
Auto-off after ten minutes of non-use in measurement mode; after one hour of non-use in calibration mode; with last reading reminder
Environment 0 to 50°C (32 to 122°F); RH max 95% non-condensing
Battery Type 9V battery
Dimensions 193 x 104 x 69 mm (7.6 x 4.1 x 2.7”)
Weight 360g (12.7oz.)
Ordering Information HI96710 is supplied with sample cuvettes (2) with caps, 9V battery, instrument quality certificate and instruction manual.