Hanna Instruments HI 99121 User manual

INSTRUCTION MANUAL
HI99121
Waterproof pH & Temperature Meter
for Direct Measurement in Soil

Thank you for choosing a Hanna Instruments product.
Please read this instruction manual carefully before using this meter.
This manual will provide you with the necessary information for correct use of
this meter, 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
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............................................................................................................
Accessories.........................................................................................................................
Electrode maintenance........................................................................................................
Certification........................................................................................................................
Recommendations for users.................................................................................................
Warranty ...........................................................................................................................
TABLE OF CONTENTS
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4
6
7
12
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6
16
11
16
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20
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4
PRELIMINARY EXAMINATION
GENERAL DESCRIPTION AND INTENDED USE
PRELIMINARY EXAMINATION
Remove the instrument and accessories from the packaging and examine it carefully to make sure
that no damage has occurred during shipping. Notify your nearest Hanna Instruments Customer
Service Center if damage is observed.
Each HI99121 is delivered in a rugged carrying case and is supplied with:
• HI12923 pH/temperature probe with conical tip, DIN connector and 1 m (3.3’) cable
• HI70004 pH 4.01 buffer (1 sachet)
• HI70007 pH 7.01 buffer (1 sachet)
• HI700663 cleaning solution for soil deposits (1 sachet)
• HI700664 cleaning solution for humus deposits (1 sachet)
• HI7051M soil sample preparation solution
• HI721319 auger for ground penetration, packed separately in a carton box
• 100 mL beaker (1 pc.)
• 1.5V AAA alkaline batteries
• Instrument quality certificate
• Electrode quality certificate
• Instruction manual
Note: Save all packing material until you are sure that the instrument works correctly. Any
damaged or defective item must be returned in its original packing material with the supplied
accessories.
GENERAL DESCRIPTION AND INTENDED USE
The HI99121 portable pH meter together with HI12923 pH electrode is designed to measure pH in
soil or soil slurries.
The HI99121 is a lightweight, portable pH and temperature meter. It features a two button operation
system and is simple to use. It has a waterproof and compact casing, large dual‑line display, and
automatic pH calibration at one or two points.
The HI12923 has a conical rugged tip. It has a built‑in temperature probe for temperature
compensated pH readings and an integrated preamplifier to provide measurements impervious to
noise and electrical interferences.
The HI721319 auger for ground penetration is supplied to loosen the soil prior to any measurements
being taken. The use of the auger is recommended to prevent scratching to the pH glass.

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 probe with integrated temperature sensor
• Probe quick connect system
• Battery life indication and low battery detection
• Keystroke confirmation tone
• Auto‑off function
• Waterproof casing IP67

6
SPECIFICATIONS
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
@ 25 °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 preamplified pH and temperature probe with conical tip,
DIN connector and 1 m (3.3’) cable
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”)
Weight (with batteries) 196 g (6.91 oz.)
Case ingress protection rating IP67
* the HI12923 is limited to be used from 0 to 12 pH and from ‑5 to 70 °C temperature (23 to 158 °F).
SPECIFICATIONSDISPLAY DESCRIPTION
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
8 Temperature unit
9 Secondary LCD
10 Meter modes indicator
11 pH calibration buffer(s) used

7
OPERATIONAL GUIDE
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“).
CONNECTING 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.
TURNING 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 signal 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,
displaying “WAIT” until electrode check is in process then the meter enters the normal measurement
mode.
Measurement
mode
Battery life
LCD
check up
→ →
→
Electrode
check
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 alternatively on the
secondary LCD with “---“ blinking on the first LCD line.
- If the probe is not compatible “WRONG” ”PROBE“ message appears alternatively 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).
SELECTING MEASUREMENT VALUES
While in measurement mode, press the SET button to select pH or pH‑mV measurement on the first
LCD line.

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 soiled, clean the electrode by soaking in cleaning solution
for 20 minutes, then rinse the tip and soak in storage solution at least 30 minutes before use.
Rinse the electrode off well and shake off excess droplets. 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 in distilled or deionized water to eliminate cross‑contamination.
For better accuracy, frequent calibration of the pH sensor with the meter is recommended. In
addition, the meter must be recalibrated:
a) whenever the pH electrode is replaced.
b) after testing aggressive chemicals.
c) when high accuracy is required.
d) at least once a month.
e) after cleaning the sensor.
FREEZING MEASUREMENT VALUES
While in measurement mode, press and hold the SET button until “HOLD“ appears on the secondary
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.
ENTERING CALIBRATION MODE
Press and hold the button until ”POWER” and tag is replaced by “STD“ and tag.
Release the button.
ENTERING SETUP MODE
Press and hold button until “STD“ and tag is replaced by “SETUP“ and tag.
Release the button.
TURNING 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, displaying
“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 (pH 6.86 for NIST)
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.
For better accuracy it is always recommended to carry out a two‑point calibration.
After the calibration procedure has been completed, the tag is turned on together with the
calibrated points.
Exiting calibration and resetting 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 and
then hydrated in storage solution for a minimum of 30 minutes before calibrating the probe.

11
METER SETUP
METER SETUP
Setup mode allows the selection of the Temperature unit, Auto‑off, Beep confirmation tone, 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, usetheSET button. After the temperature
unit has been selected, press toconfirm and to enter the “A-OFF“ selection.
• Use the SET button, to navigate 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 the beep tone ON or OFF, press the SET button; press to confirm
and to enter the calibration buffer selection “pH 7.01 BUFF“.
• To change the 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“.
• To change the pH measurement resolution between “0.1“ and “0.01“ use
the SET button; then press to confirm and to enter electrode calibration
information “INFO“ selection.
• To switch the electrode condition indicator on the LCD ON or OFF, 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.

12
SOIL pH
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.
Figure 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 (see Figure 2).
Fig. 2. Solubility of the elements according to varying pH
SOIL pH

13
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.
Soil Management Strategy with regard to pH
• It is advisable to choose crops that are suitable for the soils pH range (e.g. rice, potato,
strawberry crops have a preference for acid soil).
• 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 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
CaCO354‑90 36‑54 18‑36
Table 1. Quantity (q/ha) of pure compound necessary to increase 1 unit of pH.
SOIL pH

14
Different naturally occurring minerals may affect 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 and note what quantities provide the same result as 100 kg of gypsum.
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. Soil ameliorants.
Procedure for direct ground measurement
Note: Do not use this procedure if the soil being measured is rocky the pH electrode can be
damaged.
1) Ensure the meter is set up correctly and pH electrode is calibrated.
2) Dig and discard 5 cm (2”) of topsoil.
3) Perforate the soil with the HI721319 auger for ground penetration to a depth of 20 cm
(8”).
4) If the soil is dry, moisten it with a small amount of distilled or deionized water.
5) Wash the electrode with tap water.
6) Insert the electrode pushing it slightly into the soil to ensure the pH bulb is in contact with
the soil.
7) Allow the measurement to stabilize and record the value.
8) Wash the electrode with tap water and gently remove any soil remaining on the electrode
with your finger, this will prevent the glass from scratching.
For the best results, prepare a soil slurry using the HI7051 soil sample preparation solution.
SOIL pH

15
Procedure for the measurement of soil solution
1) Ensure meter is set up corectly and pH electrode is calibrated.
2) Sampling
a) Extract soil sample for testing. For small sample area at least 2 samples are recommended.
For larger areas take 1 sample per 1000 m2(0.25 acre). A higher number of samples
will give you better results. Take the same size sample from each location (i.e. one bag).
Avoid extracting samples with obvious anomalies and consider them separately.
Depth and extraction guidelines:
General: Dig and discard 5 cm (2”) of topsoil. Dig to a depth of 20 cm (8”).
Herbaceous crops: Dig to a depth of 20 to 40 cm (8” to 16”).
Orchards: Dig to a depth of 20 to 60 cm (8” to 24”).
b) Spread each soil sample on newspaper and let them dry in a shady place or place them
in a 40°C oven until dry. Discard any stones and plant residue.
c) Mix all of the dried samples together to obtain a homogeneous mixture.
3) Prepare soil slurry
a) Sift roughly 30 grams of the dried soil though a 2 mm sieve.
b) Weigh 10 g of soil into a beaker and add 25 mL of HI7051 soil sample preparation
solution. If necessary the sample size can be increased to 20 g and 50 mL of HI7051.
c) Mix the sample vigorously for 30 seconds.
d) Wait 5 minutes. This will allow the soil to release soluble nutrients.
4) Immerse the pH electrode into the prepared sample and swirl gently.
5) Allow the measurement to stabilize and record the value.
6) Wash the electrode with tap water and gently remove any soil remaining on the electrode
with your finger, this will prevent the glass from scratching.
SOIL pH

16
ORGANIC SUBSTRATE
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 bought substrate is that desired
(pH can change if too much time elapses from the date of packaging to the moment of utilization).
1) Ensure pH meter is set up correctly and pH electrode is calibrated.
2) Direct pot measurements
a) Add a little distilled or deionized water to the substrate if it is dry
b) Use the HI721319 auger for ground penetration to puncture the soil.
c) Insert the electrode pushing it slightly into the substrate to ensure the pH bulb is in contact
with with it.
d) Allow the measurement to stabilize and record the value.
e) Wash the electrode with tap water and gently remove any substrate remaining on the
electrode with your finger, this will prevent the glass from scratching.
3) Substrate solution
a) Extract a sample of the substrate and allow it to dry. Remove any plant residues and rocks.
b) Weigh 10 g of soil into a beaker and add 20 mL of HI7051 soil sample preparation
solution. If necessary the sample size can be increased to 20 g and 40 mL of HI7051.
c) Mix the sample vigorously for 30 seconds.
d) Wait 5 minutes. This will allow the soil to release soluble nutrients.
e) Immerse the pH electrode into the prepared sample and swirl gently.
f) Allow the measurement to stabilize and record the value.
g) Wash the electrode with tap water and gently remove any soil remaining on the electrode
with your finger, this will prevent the glass from scratching.
ORGANIC SUBSTRATE
IRRIGATION WATER
Irrigation water quality is a very important factor. If the pH value is well below pH 7, it is possible
that contaminants are present.
Ranges for evaluation of water quality:
‑ 6 to 8.5 pH: good, 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 use if possible
‑ pH<4 or pH>10: Indicates presence of contaminants. Do not use for irrigation.
IRRIGATION WATER

17
NUTRIENT SOLUTION
A rational fertilization program is required for optimum plant growth in greenhouses. pH value
of nutrient solution (water + fertilizer) has to meet plant needs.
If a fertigation system with automatic pH control is used, ensure that it is functioning properly.
Check the pH of the irrigation solution as well as of any recycled solution.
Table 3 tabulates optimum pH values for various plants.
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
Eggplant 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
NUTRIENT SOLUTION

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 6‑7.5
Hyacinth 6.5‑7.5 Tulip 6‑7
Iris 5‑6.5 Viola 5.5‑6.5
Juniper 5‑6.5
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
Dieffenbachia 5‑6 Philodendron 5‑6
Dracaena 5‑6 Yucca 6‑7.5
Freesia 6‑7.5
Table 3. Preferred pH range for various crops and plants
NUTRIENT SOLUTION

19
BATTERY REPLACEMENT
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 a few seconds then the
meter powers 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.
Replace the three 1.5V AAA alkaline batteries located in the battery compartment, observing
the indicated polarity.
Replace the battery cover making sure that the gasket is in place.
BATTERY REPLACEMENT

20
ACCESSORIES
ACCESSORIES
HI12923 Combination preamplified pH/temperature probe with conical tip, DIN
connector and 1 m (3.3’) cable
HI7004L pH 4.01 buffer solution, 500 mL
HI7006L pH 6.86 buffer solution, 500 mL
HI7007L pH 7.01 buffer solution, 500 mL
HI7009L pH 9.18 buffer solution, 500 mL
HI7010L pH 10.01 buffer solution, 500 mL
HI70300L Storage solution for pH and ORP electrodes, 500 mL
HI7061L Electrode cleaning solution for general use, 500 mL
HI7071 3.5M KCl with AgCl reference electrolyte, 30 mL, 4 pcs.
HI700663P Cleaning solution for soil deposits, 20 mL sachet, 25 pcs.
HI700664P Cleaning solution for humus deposits, 20 mL sachet, 25 pcs.
HI7051L Soil sample preparation solution, 500 mL
HI710028 Orange silicon rubber boot
HI710142 Black carrying case for HI991XX portable instruments
HI721319 Auger for ground penetration
HI76405 Electrode holder with steel base
HI77400P Calibration kit (pH 4.01 and pH 7.01 buffer solution, 20 ml sachet, 5 pcs. each)
Code and serial number on the other side
Quick connect rubber protection, 1 meter cable
Temperature sensor
Reference junction
pH tip