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£586.50 £703.80 (Inc. VAT)

Product Description

HI-99121 Waterproof pH & temperature meter for direct measurement in soil

  • Complete with pH electrode
  • 2 year manufacturer warranty

The HI-99121 portable pH meter, together with HI-12923 pH electrode, is designed to measure

pH in soil or soil slurries.

The HI-99121 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.

Main features:

  • Simultaneous pH and temperature measurements on a large dual-line LCD display
  • Automatic pH calibration at one or two points within two memorised buffer sets (standard

    or NIST)

  • Selectable temperature unit (°C or °F)
  • Electrode condition indicator
  • mV or pH measurement for electrode check
  • HI-12923 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

About 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


  • 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.

  • pH strongly influences the availability of nutrients and the presence of micro-organisms

    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

    mineralisation 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 varying pH levels.

  • Each plant needs elements in different qualities and this is the reason why each plant

    requires a particular range of pH to optimise its growth.

  • For example, iron, copper and manganese are not soluble in an alkaline environment. This

    means that plants needs these elements should theoretically be in an acidic type of soil.

    Nitrogen, phosphorus, potassium and sulphur, 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 aluminium 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.

  • Different naturally occurring minerals may affect soil pH in the same way.

Supplied with:

  • HI-12923 pH/temperature probe with conical tip, DIN Connector and 1m cable
  • HI-70004 pH 4.01 buffer (1 sachet)
  • HI-70007 pH 7.01 buffer (1 sachet)
  • HI-700663 cleaning solution for soil deposits (1 sachet)
  • HI-700664 cleaning solution for humus deposits (1 sachet)
  • HI-7051M soil sample preparation solution
  • HI-721319 auger for ground penetration, packed separately in a carton box
  • Beaker (1)
  • 1.5 AAA alkaline batteries
  • Instrument quality certificate
  • Electrode quality certificate
  • Instruction manual

The electrode, auger & soil prep solution explained

HI-12923 has a conical rugged tip. It has a built-in temperature probe for temperature

compensated pH readings and an integrated pre-amplifier to provide measurements impervious

to noise and electrical interferences.

The HI-721319 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.

For best results, it is recommended that soil tests be carried out using a prepared soil

slurry using the HI-7051 soil sample preparation solution, rather than direct €˜in the field€™

measurements – although this is possible following the instructions and use of the included


pH Range -2.00 to 16.00 pH*
Temperature Range -5.0 to 105.0°C / 23.0 to 221.0°F
pH Resolution 0.01 pH
Temperature Resolution 0.1°C / 0.1°F
pH Accuracy ±0.02 pH
Temperature Accuracy ±0.5°C (up to 60°C), ±1°C (outside);
±1.0°F (up to 140°F), ±2°F (outside)
pH Calibration automatic, 1 or 2 point with 2 sets of memorised buffer values
(pH 4.01 / 7.01 / 10.01 or pH 4.01 / 6.86 / 9.18)
Temperature Compensation Automatic, -5 to 105°C (23 to 221°F)
pH Electrode HI 12923 preamplified pH and temperature probe with conical tip,
DIN connector and 1 m (3.3′) cable (included) – The HI-12923 is limited to be used from 0

to 12 pH and from -5 to 70°C

Battery Type / Life 3 x 1.5V AAA / approx. 1400 hours of continuous use:
auto-off after 8 minutes of non-use
Environment 0 to 50°C (32 to 122°F); RH max 100%
Dimensions 154 x 63 x 30 mm (5.9 x 3.1 x 1.4″)
Weight 196g
Case ingress protection rating IP67

Please call for more information on this product.

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