Hach Chlorine Pocket Colorimeter II

Chlorine Free and Total Pocket Colorimeter II USEPA Approved for Drinking Water
Simple and Fast Operation Optional Belt Holster

The Pocket Colorimeter IITM is a complete Analysis System for Free Chlorine and Total Chlorine. It features a wide Range of 0.02 to 2.00 mg/L and 0.1 to 8.0 mg/L (ppm) and comes complete with a Reagent Set (100 tests each, low range, or 50 tests each, high range) a User Manual, a Carrying Case, and four AAA Batteries.
  • USEPA approved for drinking water
  • Range (Free and Total)
  • LR 0.02-2.00 mg/L (ppm)
  • HR 0.1-8.0 mg/L (ppm)
  • Waterproof, lightweight, economical
  • Datalog records last 10 data points
  • Simple and fast operation
  • Backlight for low light conditions
  • Battery indicator icon
  • Optional Belt Holster



QTY LHC58700-00

Hach Free & Total Chlorine Pocket Colorimeter II

QTY LHC21055-69

DPD1 Free Chlorine 10mL,pk/100 powder pillows

QTY LHC25020-25

DPD Free Chlorine AccuVac® Ampuls, pk/25 LR

QTY LHC21056-69

DPD4 Total Chlorine 10mL,pk/100 powder pillows

QTY LHC25030-25

DPD Total Chlorine AccuVac® Ampuls, pk/25 LR

QTY LHC24276-06

Glass Sample Cell with Cap 1" 10 mL pk/6

QTY LHC48643-02

Plastic Sample Cell with Cap 1" 10 mL High Range 2/pk

QTY LHC26353-00

SpecCheck Secondary Standard Kit DPD 0-2.0 mg/L

QTY LHC59531-00

Holster for Hach Pocket Colorimeter II


  • Lamp: Light Emitting Diode (LED)
  • Detector: Silicon Photocell
  • Wavelength: Fixed wavelength1 ± 2 nm
  • Filter Bandwidth: 15 nm
  • Absorbance Range: 0 to 2.5 Abs
  • Sample Cell Pathlength: 1 cm and 22 mm
  • Display: Liquid Crystal Display (LCD), backlit
  • Enclosure: IP67, waterproof at 1 m for 30 minutes
  • Operating Conditions: 0 to 50 °C, 0 to 90% RH
  • Dimensions: 3.5 x 6.1 x 15.5 cm (1.4 x 2.45 x 6.2 inches)
  • Net Weight: 0.23 kg (0.5 lbs)
  • Power: 4 AAA alkaline batteries (approximate life of 2000 Tests)
  • Compliance: European CE Mark
  • Warranty: 2 years
1. Plastic vs. glass sample cells for Pocket II Colorimeter
Problem Description
I received both glass and plastic sample cells with my Pocket Colorimeter II. Which should I use?
Problem Solution
The different sample cells correspond to different concentration ranges in the instrument. Many Pocket Colorimeters have a low and high range. For example, the Pocket Colorimeter II for Chlorine measures chlorine in a low range mode from 0.02 - 2.00 mg/L Cl2, and in a high range mode from 0.1 - 8.0 mg/L Cl2. The step-by-step procedure is different for the low vs. high range.

Glass sample cells should be used when measuring in the low range mode, and plastic cells should be used when measuring in the high range mode. If using the Pocket Colorimeter II for pH and Chlorine, use the glass sample cells when measuring pH and the plastic cells when measuring chlorine.

The plastic cells have a shorter path length, and the calibration is different when glass vs. plastic cells are used. If a glass cell is used for a range that is calibrated with a plastic sample cell, the readings will be erroneously high.

Note that the plastic cell used with older model Pocket Colorimeters will not fit correctly in the Pocket Colorimeter II.

2. HR vs. LR results using Pocket II Colorimeter
Problem Description
When I test the sample in my Pocket II Colorimeter using the high range I get one reading, and then I test the same sample on the low range and get a totally different reading. Why?
Problem Solution
The procedure is different for the 2 ranges; make sure you are following the correct procedure for the range you are using. The high range uses more reagent than the low range. The high range also uses a plastic sample cell instead of the glass cell used for the low range.
3. Chlorine standard dilutions for Pocket II Colorimeter calibration
Problem Description

How do I dilute the primary Chlorine Standard Solution to prepare calibration standards for calibrating my Pocket II Colorimeter for Chlorine?

Problem Solution

If you are required to calibrate your Pocket II Colorimeter, you will need to prepare several (typically 5 to 7) primary calibration standards at different concentrations. The calibration standards should span the full concentration range of the test you use. For example, if you use a Hach method that measures from 0 - 2.00 mg/L, prepare calibration standard concentrations that span this range, for example 0.3, 0.6, 0.9, 1.2, 1.6, and 1.9 mg/L Cl2.

The following procedure is one way to accurately prepare 6 chlorine calibration standards from a Hach Chlorine Standard Solution.

Required Items:

  • Chlorine Standard Solution, 50-75 mg/L (actual concentration on label)
  • Flasks, volumetric, class A, glass, 200-mL
  • Pipets, volumetric, class A, glass, 1, 2, 3, 4, 5, and 6 mL
  • Pipet Filler
  • Deionized water

Diluting the Chlorine Standard Solution:

  1. Fill a 200-mL volumetric flask approximately half full with deionized water.
  2. Open a chlorine standard solution ampule.
  3. Pipet 1 mL of the chlorine standard solution into the flask.
  4. Fill the flask to the mark with deionized water, stopper, and invert repeatedly to mix. This makes an approximately 0.3 mg/L Cl2 standard solution. (Use the equation below to find the exact concentration.)
  5. Prepare additional standards by repeating the above steps, substituting 2, 3, 4, 5, and 6 mL of the chlorine standard solution for the 1 mL shown in step 3.

Calculating the Concentration:

Because Chlorine Standard Solutions are difficult to prepare accurately, Hach targets a concentration range, in this case 50 to 75 mg/L, and then determines the actual concentration by amperometric titration. You will find the actual concentration on the label. Use this concentration to calculate each of your calibration standard concentrations.

Multiply the concentration from the Chlorine Standard Solution label by the multipliers in the following table. 

Standard # Pipet volume (mL) Multiplier

1 1 0.005
2 2 0.01
3 3 0.015
4 4 0.02
5 5 0.025
6 6 0.03

Diluted concentration = chlorine ampule concentration x multiplier

Example: Your chlorine standard solution is 63.1 mg/L. You pipetted one mL of this standard into a 200-mL flask and diluted to the mark. The concentration of your diluted standard is 63.1 x 0.005 = 0.32 mg/L chlorine. Enter 0.32 in the calibration mode of your Pocket II Colorimeter for standard 1. Measure the absorbance of this standard after adding the DPD reagent.

Note: Use the diluted standard solutions as soon as possible after mixing.

4. Holster carrying case for Pocket Colorimeter II
Problem Description
Is there a very small carrying case for the Pocket Colorimeter II?
Problem Solution

The Pocket Colorimeter II Holster, is a carrying case made from durable fabric. Place your instrument, sample vials, and reagents in the holster. Then place the holster on your belt for convenience when taking field measurements.