Hanna Instruments HI 99121 User manual

INSTRUCTION MANUAL
HI99121
Direct Soil pH Portable Meter

Thank you for choosing a Hanna Instruments product.
Please read this instruction manual carefully before using the instrument.
This manual will provide you with the necessary information for correct use of
the instrument, as well as a precise idea of its versatility.
If you need additional technical information, do not hesitate to e‑mail us at
[email protected] or view our worldwide contact list at www.hannainst.com.
All rights are reserved. Reproduction in whole or in part is prohibited without the written consent of the
copyright owner, Hanna Instruments Inc., Woonsocket, Rhode Island, 02895, USA.
Dear
Customer,

3
Table of Contents................................................................................................................
Preliminary Examination .....................................................................................................
General Description and Intended Use..................................................................................
Main Features....................................................................................................................
Specifications.....................................................................................................................
Display Description.............................................................................................................
Operational Guide ..............................................................................................................
Meter Setup.......................................................................................................................
Soil pH..............................................................................................................................
Organic Substrate...............................................................................................................
Irrigation Water..................................................................................................................
Nutrient Solution................................................................................................................
Battery Replacement...........................................................................................................
Electrode Maintenance........................................................................................................
Accessories.........................................................................................................................
Certification........................................................................................................................
Recommendation for Users..................................................................................................
Warranty ...........................................................................................................................
TABLE OF CONTENTS
4
4
6
7
12
5
6
16
11
16
3
17
19
20
21
22
23
23

4
PRELIMINARY EXAMINATION
GENERAL DESCRIPTION and INTENDED USE
Remove the meter from the packing material and examine it carefully to make sure that no
damage has occurred during shipment. If noticeable damage is evident, contact your local Hanna
Instruments Office.
Each meter is supplied complete with:
• HI12923 pH/temperature probe
• pH 4.01 & 7.01 Buffer sachet
• HI700663 electrode cleaning solution for soil deposits (1 sachet)
• HI700664 electrode cleaning solution for humus deposits (1 sachet)
• HI7051M soil preparation solution
• HI721319 ground auger
• 100 mL beaker (1 pc.)
• Alkaline batteries: 1.5V AAA (3 pcs.)
• Rugged carrying case
• Calibration certificate of meter
• Calibration certificate of probe
• Instruction manual
Note: Save all packing material until you are sure that the meter functions correctly. All
defective items must be returned in the original packing together with the supplied accessories.
The HI99121 is the perfect portable pH meter for soil testing. With the HI99121 and HI12923
direct soil pre‑amplified pH and temperature probe, users can test both the pH of soil directly or after
preparation of a soil slurry with deionized water.
The HI12923 features a conical, rugged tip that can be directly used in soil. A plastic auger is sup‑
plied to perforate and loosen the soil prior to sensor measurement. Use this tool to prevent scratching
the pH sensitive glass on nutrient crystals or small pebbles.

5
MAIN FEATURES
Main features:
• Simultaneous pH and temperature measurements on a large dual‑line LCD display
• Automatic pH calibration at one or two points within two memorized buffer sets (standard or
NIST)
• Selectable temperature unit (°C or °F)
• Electrode condition indicator
• mV of pH measurement for electrode check
• HI12923 dedicated pH with integral temperature sensor
• Probe quick connect system
• Battery life indication and low battery detection
• Keystroke confirmation tone
• Auto‑off function
• Waterproof casing IP67

6
Range*
‑2.00 to 16.00 pH / ‑2.0 to 16.0 pH
±825 mV (pH‑mV)
‑5.0 to 105.0 °C/23.0 to 221.0 °F
Resolution
0.01 pH / 0.1 pH
1 mV
0.1 °C/0.1 °F
Accuracy
@ 20 °C / 68 °F
±0.02 pH / ±0.1 pH
±1 mV (pH‑mV)
±0.5 °C up to 60 °C; ±1.0 °C outside
±1.0 °F up to 140 °F; ±2.0 °F outside
Temperature
compensation
Automatic
‑5.0 to 105.0 °C/23.0 to 221.0 °F
pH Calibration Automatic, 1 or 2 point selectable buffer set Standard: 4.01;7.01;10.01 or
NIST: 4.01;6.86;9.18
Probe (included) HI12923 glass body, pre‑amplified pH electrode for soil measurement with internal
temperature sensor, DIN connector and 1 m (3.3’) cable (included)
Battery type / life 1.5V AAA (3 pcs.)
approx. 1400 hours of continuous use
Auto‑Off user selectable: after 8 min, 60 min or disabled
Environment 0 to 50 °C (32 to 122 °F)
RH max. 100%
Meter Dimensions 154 x 63 x 30 mm (6.1 x 2.5 x 1.2”)
Meter Mass
(with batteries) 196 g (6.91 oz.)
Case Ingress Protection
Rating
IP67
SPECIFICATIONS
* the HI12923 is limited to be used from 0‑12 pH and from ‑5 to 70 °C temperature (23 to 158 °F).
DISPLAY DESCRIPTION
1 Automatic Temperature Compensation
indicator
2 Stability indicator
3 Battery percentage
4 Electrode condition indicator
5 Low battery indicator
6 Measurement unit
7 Primary LCD

7
OPERATIONAL GUIDE
Each meter is supplied with batteries. Before using the meter for the first time, open the battery
compartment and insert batteries, observing the polarity (see “Battery Replacement“).
TO CONNECT THE ELECTRODE
With the meter turned off, connect the HI12923 probe to the DIN socket on the bottom of the meter
by aligning the pins and pushing in the plug firmly. Remove the protective cap from the probe before
taking any measurements.
TO TURN THE METER ON
To turn the meter ON, press the button on the front of the meter. If it does not turn on, make sure
that the batteries are properly installed in their place. The meter is provided with an active acoustic
tone that confirms when a key is pressed. At start‑up the meter displays all LCD segments for a
few seconds, followed by the percentage indication of the remaining battery life, displays “WAIT”
while doing an electrode check and then enters the normal measurement mode.
Note: The meter detects the presence and the type of the probe at its input.
- If the probe is not connected the message “NO” ”PROBE“ appears on the secondary LCD with
“---“ blinking on the first LCD line.
- If the probe is not compatible “WRONG” ”PROBE“ message appears on the secondary LCD
with “---“ blinking on the first LCD line.
- If the readings are out of range, the nearest range limits are displayed blinking (E.g. -2.00 pH
-5.0 °C).
TO SELECT THE MEASUREMENT RANGE
While in measurement mode, press the SET button to select pH or pH‑mV measurement on the first
LCD line.
Measurement
mode
Battery life
LCD
check up
→ →
→
Electrode
check
8 Temperature unit 9 Secondary LCD
10 Meter modes indicator 11 pH calibration buffer(s) used

8
OPERATIONAL GUIDE
pH MEASUREMENT & CALIBRATION
Make sure the meter has been calibrated before use. If the probe is dry, soak it in HI70300 storage
solution for 30 minutes to reactivate it. If fouled, clean the electrode before use. Soak the electrode
tip in cleaning solution for 20 minutes, then rinse in clean water and soak for 30 minutes in electrode
storage solution to rehydrate it. Recalibrate before using. Submerge the probe in the sample to be
tested while stirring it gently. Wait until the tag on the LCD disappears.
The LCD displays the pH value (automatically compensated for temperature) on
the primary LCD, while the secondary LCD displays the sample temperature.
If measurements are taken in different samples successively, rinse the probe tip
thoroughly†to eliminate cross‑contamination. After cleaning, rinse the probe tip
with some deionized water and some of the sample to be measured.
For better accuracy, frequent calibration of the pH sensor with the meter is recommended. In
addition, the meter must be recalibrated whenever:
a) The pH electrode is replaced.
b) After testing aggressive chemicals.
c) Where high accuracy is required.
d) At least once a month.
e) After cleaning the sensor.
†The probe tip should be rinsed with purified water (reverse osmosis, distilled, or deionized) before and after placing in any solution
(buffer, storage, or sample).
→
TO FREEZE THE MEASUREMENT VALUES
While in measurement mode, press and hold the SET button until “HOLD“ appears on the second‑
ary LCD. The “HOLD“ remains for 1 second and reading of pH, mV and temperature will be
frozen on the LCD with “H” blinking.
Press any button to resume active measurements.
TO ENTER CALIBRATION MODE
Press and hold the button until ”POWER” and tag is replaced by “STD“ and tag.
Release the button.
TO ENTER SETUP MODE
Press and hold button until “STD“ and tag is replaced by “SETUP“ and tag.
Release the button.
TO TURN THE METER OFF
While in measurement mode, press the button.”POWER” and tag will appear. Release
the button.

9
OPERATIONAL GUIDE
pH calibration
Enter calibration mode while in pH measurement mode. Place the sensor into the
first calibration buffer. If performing a two‑point calibration, use pH 7.01 (pH
6.86 for NIST) buffer first. The meter will enter the calibration mode, display‑
ing “pH 7.01 USE” and tag blinking (or “pH 6.86 USE” for NIST).
Follow directions for single and two‑point calibration below:
Single-point calibration
1. Place the probe in any buffer from the selected buffer set. The meter will automatically recognize
the buffer value.
2. If the buffer is not recognized or the calibration offset is out of the accepted range “---- WRONG“
is displayed.
3. If the buffer is recognized “REC“ is displayed then “WAIT“ until the calibration is accepted.
If using pH 7.01 (or pH 6.86 for NIST), after acceptance of the buffer press any key to exit. The
”SAVE” message is displayed and the meter returns to pH measurement mode.
If using pH 4.01 or 10.01 (or pH 9.18 for NIST) buffer the ”SAVE” message is displayed and
meter returns to pH measurement mode.
Two-point calibration
Proceed with steps 1 through 3 under single point calibration using 7.01 (pH 6.86 for NIST) pH
buffer first. Then follow steps below:
The ”pH 4.01 USE” message is then displayed.
Place the probe in the second calibration buffer (pH 4.01 or 10.01, or, if using NIST, pH 4.01
or 9.18). When the second buffer is accepted, the LCD will display “SAVE” for 1 second and the
meter will return to the normal measurement mode.
If the buffer is not recognized or the slope is out of accepted range ”--- WRONG” is displayed.
Change the buffer, clean the electrode or press any key to exit calibration.
It is always recommended to carry out a two‑point calibration for better accuracy.
When the calibration procedure is completed, the tag is turned on together with the calibrated
points.
To exit calibration and reset default values
After entering the calibration mode and before the first point is accepted, it is possible to quit the
procedure and return to the last calibration data by pressing the button. The LCD displays “ESC“
for 1 second and the meter returns to normal mode.
To reset the default values and clear a previous calibration, press the SET button after entering the
calibration mode and before the first point is accepted.
The LCD displays “CLEAR“ for 1 second, the meter resets to the default calibration and the
tag with the calibrated points on the LCD disappears.

10
OPERATIONAL GUIDE
ELECTRODE CONDITION
The display is provided with a probe icon (unless the feature is disabled from setup) which indicates
the electrode status after calibration. The “condition” remains active for 12 hours (unless the
batteries are removed).
The electrode condition is evaluated only if the current calibration has two points.
5 bars: excellent condition
4 bars: very good condition
3 bars: good condition
2 bars: fair condition
1 bar: poor condition
1 bar blinking: very poor condition
With 1 bar it is recommended to clean the electrode and recalibrate. If there is still only 1 bar or
1 bar blinking replace the probe.
Sensor Check
Setting the meter to pH‑mV range the user can check the sensor status at any time. The offset
value is the reading in pH 7.01 buffer (@ 25 °C/77 °F). If this reading is outside the range
±30 mV, the electrode is considered “very poor”. The slope value of the sensor is the difference
between readings in pH 7.01 and in pH 4.01 buffers. When the slope reaches the value of about
150 mV, the electrode is considered “very poor“. When “poor“ or “very poor“, it is recommended
to replace it with a new one.
Note: To ensure reliable readings, the electrode must be cleaned with cleaning solution before
measuring the offset and the slope.

11
METER SETUP
Setup mode allows the selection of the Temperature unit, Auto‑off, Beep, the type of pH buffer set, the
Resolution and Information. To enter Setup mode press and hold button until “STD“ and
tag is replaced by “SETUP“ and tag. Release the button.
• “TEMP“ is displayed on the secondary LCD with the current temperature unit
(E.g. “TEMP °C“), for °C/°F selection, use the SET button. After the tem‑
perature unit has been selected, press to confirm and to enter the “A-OFF“
selection.
• Use the SET button, to cycle through the auto‑off choices: 8 minutes (“8”,
default value), 60 minutes (“60”) or disabled (“---”). Press to confirm
and to enter the “BEEP“ selection.
• To switch ON or OFF the beep tone, press the SET button; press to confirm
and to enter the calibration buffer selection “pH 7.01 BUFF“.
• To change the type of calibration buffer set, the meter will show the current
buffer set: “pH 7.01 BUFF” (for standard buffer set: 4.01/7.01/ 10.01) or “pH
6.86 BUFF” (for NIST buffer set: 4.01/6.86/ 9.18). Change the set with the
SET button. Press to confirm and to enter pH resolution selection “RESOL“.
• TochangethepHmeasurementresolutionbetween “0.1“and“0.01“usetheSET
button; then press to confirm and to enter electrode calibration information
“INFO“ selection.
• To switch ON or OFF the electrode condition indicator on the LCD, press the SET
button; press to exit setup options; Change the set with the SET button,
then press to confirm and to return to normal mode.

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pH is the measure of the hydrogen ion concentration [H+]. The pH scale goes from 0 (very acidic) to
14 (basic) with pH 7 being neutral. Soil can be acid, neutral or alkaline.
Fig. 1. shows the relationship between the scale of pH and types of soil. Most plants prefer a pH
range from 5.5 to 7.5; but some species prefer more acid or alkaline soils. Nevertheless, every
plant has a target for optimum growth.
Fig. 1. Types of soil according to the pH value
pH strongly influences the availability of nutrients and the presence of microorganisms and plants
in the soil.
For example, fungi prefer acidic conditions whereas most bacteria, especially those supplying
nutrients to the plants, have a preference for moderately acidic or slightly alkaline soils. In fact, in
strongly acidic conditions, nitrogen fixing and the mineralization of vegetable residual is reduced.
Plants absorb the nutrients dissolved in the soil water and the nutrient solubility depends largely
on the pH value. Hence, the availability of elements is different at different pH levels (Fig. 2).
SOIL pH
Fig. 2. Solubility of the elements according to varying pH

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Each plant needs elements in different quantities and this is the reason why each plant requires
a particular range of pH to optimize its growth.
For example, iron, copper and manganese are not soluble in an alkaline environment. This means
that plants needing these elements should theoretically be in an acidic type of soil. Nitrogen,
phosphorus, potassium and sulfur, on the other hand, are readily available in a pH range close
to neutrality.
Abnormal pH values may increase the concentration of toxic elements for plants. For example,
a plant may not tolerate an excess of aluminum ions that may increase under acidic conditions.
When pH values are too far from neutral conditions a less permeable and more compact soil
may result.
A Soil Management Strategy with regard to pH
• It is advisable to choose crops that are suitable for the soils pH range (e.g. in an acid soil,
cultivate rice, potato, strawberry).
• Add fertilizers that do not increase acidity (urea, calcium nitrate, ammonium nitrate and
superphosphate) or lower alkalinity (ammonium sulfate).
• A cost evaluation should be made prior to soil pH modification to determine cost of soil
ameliorants versus value of plants grown.
• pH modification may produce critical improvement in plant performance but may take too
long or be short lived.
For example, by adding lime, the effects in clay soil can last for as long as 10 years, but only
2‑3 years in a sandy soil.
For an acid soil, we can use substances such as lime, dolomitic, limestone and marl, according
to the nature of the soil. See Table 1.
SOIL pH
Soil Ameliorants Clay soil Silty soil Sandy soil
CaO 30‑50 20‑30 10‑20
Ca(OH)239‑66 26‑39 13‑26
CaMg(CO3)249‑82 33‑49 16‑33
Ca CO354‑90 36‑54 18‑36
Table 1. Quantity (q/ha) of pure compound necessary to increase 1 unit of pH.

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Different naturally occurring minerals may effect soil pH the same way, but the method for
correction may differ. Take for example elevated soil pH:
‑ Soils rich with limestone:
Add organic matter (non‑organic ameliorants such as sulfur and sulfuric acid might not make
economic sense due to the large quantities needed).
‑ Alkaline‑saline soils:
An appropriate use of irrigation can provide positive results (drop‑irrigation) by flushing out salts.
If alkalinity is caused by sodium, it is recommended to add substances such as gypsum (calcium
sulfate), sulfur or other sulfuric compounds. In this case, a cost evaluation is necessary. See Table 2.
SOIL pH
Soil ameliorants (pure compounds) Quantity (kg)
Calcium chloride: CaCl2· 2H2O85
Sulfuric acid: H2SO457
Sulfur: S 19
Iron sulfate: Fe2 (SO4)3 · 7H2O162
Aluminum sulfate: Al2 (SO4)3129
Table 2. Quantities provide the same result as 100 kg of gypsum.
Procedure for direct ground measurement
1) Verify meter is set up correctly and pH electrode is calibrated.
2) Dig, discarding 5 cm of topsoil.
3) Perforate the soil (with HI721319 soil auger) to a depth of about 20 cm or more.
4) If the soil is dry, moisten it with a small amount of distilled water
5) Wash the electrode with tap water (not distilled).
6) Insert the electrode pushing it slightly into the soil to ensure proper contact.
7) Observe the measurement.
8) Wash the electrode with tap water (not distilled) and (using a finger) gently remove any
soil remaining on the electrode (avoid using a rag or cloth).
9) Repeat the procedure in different locations in the field.
10) Consider the average of the measured data.

15
For best results, it is advisable to measure the pH of a soil solution, using a sample of soil and
soil preparation solution HI7051. It is better to use this procedure if you have to test a stony
field in which you risk damaging the electrode.
Procedure for the measurement of soil solution (1:2,5)
A) Verify meter is set up corectly and pH electrode is calibrated.
B) Sampling
1) Extracting Soil Sample.
Take 1 sample per 1000 m2(0.25 acre) of homogeneous area. Even for small areas,
2 samples are recommended (the more the samples, the better the end‑results, because the
result is more representative).
2) Avoid extracting samples from soil presenting obvious anomalies and consider them separately.
3) Sample quantity:
Take the same quantity of soil for each sample. For example, use bags with similar dimensions
(1 bag per sample).
4) Depth of extraction:
General: dig and discard 5 cm (2”) of topsoil.
Herbaceous crops: from 20 to 40 cm of depth (8” to 16”).
Orchards: from 20 to 60 cm of depth (8” to 24’’).
5) Spread the soil samples on the pages of a newspaper and let the soil dry in a shady place
or put it in an oven at 40 °C.
6) Crumble the dried soil and mix all the samples together to obtain a homogeneous mixture,
discarding stones and vegetable residues.
7) From this mixture, take the soil sample for analysis.
C) Soil solution preparation and measurement
1) Sift the soil at 2 mm.
2) Weigh 10 g of soil and put it in 25 mL of soil preparation solution HI7051 (use the apposite
beaker) or 20 g of soil per 50 mL of soil preparation solution HI7051.
3) Mix for 30 seconds. Homogenize the sample by vigorous mixing.
4) Wait for about 5 minutes to allow the soil to release soluble nutrients.
5) Mix again and immerse the pH electrode into the prepared sample and swirl to ensure
maximum solution contact.
6) Wait for a stable reading before recording the measurement.
SOIL pH

16
The pH measurement of organic substrates is important in greenhouses and nursery growing pots.
pH should be checked at the outset to make sure that the pH of the substrate bought is that
desired (pH can change if too much time elapses from the date of packaging to the moment
of utilization).
A) Verify pH meter is set up correctly and pH electrode is calibrated.
B) Direct measurement in pot:
If the substrate is dry, add a little distilled water. Use the auger tool to puncture the soil. Insert
the electrode into the soil hole and wait for a stable reading, before recording the measurement.
C) Measurement of the organic substrate solution (1:2):
Let the substrate dry and discard the coarse vegetable residues and pebbles.
Prepare a solution composed of 1 part of mould and 2 parts of HI7051 solution (for example: fill the
beaker with the substrate up to 50 mL, press it gently, empty the content in another container and add
100 mL of HI7051 solution).
Homogenize the sample for 30 seconds and then wait for 5 minutes to allow the soil to release
soluble nutrients into the solution. Mix again and immerse the pH electrode into the prepared
sample and swirl to ensure maximum solution contact.
ORGANIC SUBSTRATE
The quality of irrigation water is a very important factor. If the pH value is very far from pH 7,
it is possible that other anomalies are present.
Ranges for evaluation of water quality:
‑ 6 to 8.5 pH: good, it can be utilized without problems.
‑ 5 to 6 pH or 8.5 to 9 pH: sufficient, sensitive crops could have problems.
‑ 4 to 5 pH or 9 to 10 pH: Use carefully, avoid wetting the vegetation/avoid use if possible.
‑ pH<4 or pH>10: Other anomalies that have to be identified via chemical analysis. Do not
use for irrigation.
IRRIGATION WATER

17
A rational fertilization program is required for optimum plant growth in greenhouses. The pH
value of the nutrient solution (water + fertilizer) has to meet the plants need.
If a fertirrigation system with automatic pH control is used, ensure that it is functioning properly.
Check the pH of the irrigation solution as well as any recycled solution.
Table 3. tabulates optimum pH values for various plants.
NUTRIENT SOLUTION
ORCHARD PLANTS
Preferred pH Range Preferred pH Range
Apple 5‑6.5 Orange 5‑7
Apricot 6‑7 Peach 6‑7.5
Cherry 6‑7.5 Pear 6‑7.5
Grapefruit 6‑7.5 Plum 6‑7.5
Grapevine 6‑7 Pomegranate 5.5‑6.5
Lemon 6‑7 Walnut 6‑8
Nectarine 6‑7.5
VEGETABLES AND HERBACEOUS CULTIVATIONS
Preferred pH Range Preferred pH Range
Artichoke 6.5‑7.5 Pepper 6‑7
Asparagus 6‑8 Early Potato 4.5‑6
Barley 6‑7 Late Potato 4.5‑6
Bean 6‑7.5 Sweet Potato 5.5‑6
Brussels Sprout 6‑7.5 Pumpkin 5.5‑7.5
Early carrot 5.5‑7 Rice 5‑6.5
Late carrot 5.5‑7 Soybean 5.5‑6.5
Cucumber 5.5‑7.5 Spinach 6‑7.5
Egg Plant 5.5‑7 Strawberry 5‑7.5
Lettuce 6‑7 String 6‑7.5
Maize 6‑7.5 Sugar beet 6‑7
Melon 5.5‑6.5 Sunflower 6‑7.5
Oat 6‑7 Tomato 5.5‑6.5
Onion 6‑7 Watermelon 5.5‑6.5
Pea 6‑7.5 Wheat 6‑7

18
LAWN
Preferred pH Range
Lawn 6‑7.5
GARDEN PLANTS AND FLOWERS
Preferred pH Range Preferred pH Range
Acacia 6‑8 Ligustrum 5‑7.5
Acanthus 6‑7 Magnolia 5‑6
Amaranth 6‑6.5 Narcissus 6‑8,5
Bougainvillea 5.5‑7.5 Oleander 6‑7.5
Dahlia 6‑7.5 Paulownia 6‑8
Erica 4.5‑6 Portulaca 5.5‑7.5
Euphorbia 6‑7 Primula 6‑7.5
Fuchsia 5.5‑7.5 Rhododendron 4.5‑6
Gentian 5‑7.5 Roses 5.5‑7
Gladiolus 6‑7 Sedum 6‑7.5
Hellebore 6‑7.5 Sunflower 5‑7
Hyacinth 6.5‑7.5 Tulip 6‑7
Iris 5‑6.5 Viola 5.5‑6.5
Juniper 5‑6.5
NUTRIENT SOLUTION
HOUSE PLANTS
Preferred pH Range Preferred pH Range
Abutilon 5.5‑6.5 Gardenia 5‑6
African violet 6‑7 Geranium 6‑8
Anthurium 5‑6 Hibiscus 6‑8
Araucaria 5‑6 Jasmine 5.5‑7
Azalea 4.5‑6 Kalanchoe 6‑7.5
Begonia 5.5‑7.5 Mimosa 5‑7
Camellia 4.5‑5.5 Orchid 4.5‑5.5
Croton 5‑6 Palms 6‑7.5
Cyclamen 6‑7 Peperomia 5‑6

19
Dieffenbachia 5‑6 Philodendron 5‑6
Dracaena 5‑6 Yucca 6‑7.5
Freesia 6‑7.5
Table 3. Optimum pH for various Plants.
NUTRIENT SOLUTION
Replace the three 1.5V AAA alkaline batteries located in the battery compartment, observing
the indicated polarity.
When the remaining battery life is less than 10% the battery tag blinks on the
display to warn the user.
Battery Error Prevention System (BEPS)
If the battery is too weak (“0%”) the display shows “bAtt“, “DEAD“ for few seconds then the
meter power off. Immediately replace the batteries with new ones.
The batteries are accessed by opening the battery cover on the back of the instrument. Remove
protective boot if present.
BATTERY REPLACEMENT
Replace the battery cover making sure that the gasket is in place.
BATTERY REPLACEMENT

20
ELECTRODE MAINTENANCE
PREPARATION
• Remove the protective cap. DO NOT BE ALARMED IF ANY SALT DEPOSITS ARE PRESENT. Rinse with water.
• Shake the electrode down as you would do with a clinical thermometer to eliminate any air bubbles
inside the glass bulb.
• Remove the fill hole cover to ensure the reference junctions are flowing. Set aside for storage.
• Top off the electrolyte filling solution using HI7071 solution.
• If the bulb and/or junction are dry, soak the electrode in HI70300 Storage Solution for at least
30 minutes.
• Rinse with water.
• Calibrate before using.
Loss of shielding due to low electrolyte level: Empty electrolyte with a syringe and refill with fresh HI7071.
STORAGE
• To ensure a quick response, the glass bulb and the junction should be kept moist and not allowed to dry.
• Replace protective cap with a few drops of HI70300 Storage Solution. Follow PREPARATION above
before taking measurements.
• Replace the fill hole cover.
Note: NEVER STORE THE ELECTRODE IN DISTILLED WATER.
PERIODIC MAINTENANCE
• INSPECT the electrode for any scratches or cracks. If any present, replace the electrode.
• Rinse off any salt deposits with water.
• Follow the STORAGE procedure above.
CLEANING PROCEDURE
A frequent cleaning of the pH electrode is strongly recommended to ensure correct calibration and reliable
readings.
Hanna Instruments has developed a complete series of cleaning solutions dedicated to specific applications
and kind of dirt that has to be removed from the electrode.
In soil measurements you can choose between two different solutions accordingly to the type of tested soil:
• HI700663 is indicated for inorganic soil deposits (as minerals, limestone, adsorbed clays)
• HI700664 is specific for organic soil deposits (humus)
If cleaning is performed frequently, soak the electrode in the specific solution for a few minutes.
If the electrode has not be cleaned for a while, for a complete removal of soil deposits, proceed as follows:
• wipe the electrode body (not bulb) with paper or soft tissue
• rub the reference with abrasive paper
• immerse into cleaning solution for at least 20 minutes
• rinse the sensor with water and place in storage solution for a minimum of 30 minutes recalibrate
the probe before using.
IMPORTANT: After performing any of the cleaning procedures rinse the electrode thoroughly with
distilled water. Soak the electrode in HI70300 storage solution for at least of 30 minutes. Rinse with
water. Calibrate before using.
TROUBLESHOOTING
• pH Meter: Follow the meter’s operating and calibration procedures.
• Electrode: Evaluate your electrode performance based on the SENSOR CHECK procedure on page 10.