Portable Dissolved Oxygen Meters — HORIBA LAQUA DO210-K, DO220-K, PD210-K & PD220-K

Dissolved oxygen (DO) is the concentration of oxygen dissolved in water, expressed in mg/L (ppm) or percentage saturation. It is one of the most critical indicators of water quality — supporting aquatic life, driving biological treatment processes in wastewater systems, and serving as a key compliance parameter across environmental monitoring, aquaculture, and drinking water treatment.

HORIBA Australia supplies four portable dissolved oxygen meters from their LAQUA range. The DO210-K and DO220-K are dedicated dissolved oxygen and temperature meters. The PD210-K and PD220-K are dual-channel meters adding pH and ORP measurement alongside DO. All four include the 9552-20D galvanic dissolved oxygen probe with 2m cable, are IP67 rated, and carry a 3-year warranty.

Australian Scientific is the authorised Australian agent for HORIBA water quality instruments. Contact us if you need help selecting the right model for your application.

Choose Your Dissolved Oxygen Meter

What Does a Portable Dissolved Oxygen Meter Measure?

All four meters measure dissolved oxygen and temperature from the same galvanic probe (9552-20D, 2m cable). The PD210-K and PD220-K add a second channel for pH and ORP.

Dissolved Oxygen (DO) — mg/L and % Saturation
Dissolved oxygen is measured as both concentration (mg/L or ppm) and percentage saturation (0–200.0%). The 9552-20D galvanic probe uses a Clark-type electrochemical cell — no warm-up time is required, and the sensor responds immediately on contact with the sample. Range: 0–20.00 mg/L and 0–200.0% saturation. Accuracy: ±0.2 mg/L or ±2.0% saturation. Salinity compensation is user-adjustable to account for the lower oxygen solubility of saline and brackish water.

Temperature
Integrated temperature sensor built into the DO probe measures 0.0–50.0°C with ±0.3°C accuracy. All DO measurements include automatic temperature compensation (ATC) — water temperature directly affects oxygen solubility and dissolved oxygen percentage saturation, so accurate temperature measurement is critical for correct DO readings.

pH — PD210-K and PD220-K
The dual-channel PD models add pH measurement via the included 9652-10D plastic-body, gel-filled pH/temperature electrode (2m cable). pH range: 0.00–14.00 pH, accuracy ±0.02 pH. Up to 5-point automatic calibration using pH 4.00, 7.00, and 10.01 buffer solutions (included).

ORP (Oxidation-Reduction Potential) — PD210-K and PD220-K
ORP is measured via the pH channel. An ORP electrode (9300-10D, sold separately) replaces the pH electrode when ORP measurement is required. Range: -2000 to +2000 mV, accuracy ±5 mV.

Key Features

Galvanic DO Probe — No Warm-Up Required
The 9552-20D uses a galvanic (self-generating) electrochemical cell rather than a polarographic (Clark electrode) design. Galvanic probes generate their own current without applying a voltage — they require no warm-up time and are ready to measure immediately on immersion. The 2m cable allows measurement in tanks, rivers, ponds, and shallow bores without needing to extend the meter into the water.

IP67 Waterproof and Shock-Resistant Housing
All four meters are IP67 rated — fully dustproof and protected against temporary immersion. The polycarbonate housing is shock and scratch-resistant with a non-slip grip, designed for field use in aquaculture sites, treatment plants, and environmental survey conditions.

Salinity and Barometric Pressure Compensation
Dissolved oxygen solubility varies with salinity and altitude (barometric pressure). Both are user-adjustable on all four meters — salinity compensation from 0.0 to 40.0 ppt, and altitude/pressure compensation from 0 to 4,000m or 80.0 to 106.7 kPa. Correct compensation is essential for accurate DO measurements in marine, estuarine, and high-altitude applications.

Data Logging — DO220-K and PD220-K
The DO220-K and PD220-K store up to 1,000 data sets with real-time clock and date/time stamp for full GLP-compliant data management. Data transfers to PC via USB and to printer via RS232. The DO210-K and PD210-K store 500 data points but connect via phono jack for firmware upgrades only — not data export. Choose the 220 models where dated data records and USB export are required.

Membrane Cap Replacement
The galvanic probe uses a replaceable membrane cap (9552-20C) which should be replaced every 3–6 months or when membrane fouling affects readings. Replacement membrane caps and electrolyte solution are available separately. See our calibration solutions and accessories range.

Applications for Portable Dissolved Oxygen Meters

Aquaculture and Fish Hatcheries
Dissolved oxygen is the single most critical parameter in intensive aquaculture management. Fish and crustacean health deteriorates rapidly when DO falls below species-specific thresholds — typically 5–6 mg/L for most finfish. The galvanic probe’s instant response and IP67 rating make the DO210-K and DO220-K practical for daily monitoring across multiple ponds, tanks, or sea cages. Where pH monitoring is also required, the PD210-K or PD220-K combines both parameters in a single instrument.

Environmental Monitoring and Field Surveys
DO is a standard measurement in river, lake, wetland, and estuary assessments. It indicates organic load, eutrophication, and the capacity of a water body to support aquatic life. Data logging with date and time stamping on the DO220-K and PD220-K supports the traceable, time-stamped records required for regulatory reporting.

Wastewater Treatment
DO control is fundamental to biological wastewater treatment — aerobic zones require adequate DO to sustain bacterial activity, while anoxic zones require near-zero DO for denitrification. Portable DO meters allow operators to verify dissolved oxygen levels at specific points in the treatment process, supplementing fixed online sensors. ORP measurement (PD models) is used alongside DO to characterise redox conditions in anoxic and anaerobic zones.

Drinking Water Treatment
DO is monitored in drinking water treatment as an indicator of organic contamination and to verify aeration effectiveness. It is particularly relevant in surface water treatment where seasonal stratification and algal activity can cause significant DO variation.

Industrial Process Water
Low DO is required in boiler feedwater and certain industrial processes to prevent corrosion. Portable dissolved oxygen meters with salinity and pressure compensation are used to verify DO levels in treated water prior to use in process applications.

Kit Contents and Accessories

All four kits include the 9552-20D galvanic DO/temperature probe with 2m cable. Full kit contents by model:

• DO210-K and DO220-K: LAQUAact DO210 or DO220 meter, 9552-20D galvanic DO/Temp probe with 2m cable, membrane cap spares, 2 x AA batteries, carrying case, quick guide
• PD210-K and PD220-K: LAQUAact PD210 or PD220 meter (dual channel), 9552-20D galvanic DO/Temp probe with 2m cable, 9652-10D plastic-body gel-filled pH/Temp electrode with 2m cable, pH 4.00, 7.00, 10.01 buffer solutions (60ml each), electrode adapter, membrane cap spares, 2 x AA batteries, carrying case, quick guide. Note: ORP electrode (9300-10D) sold separately.

Replacement membrane caps, electrolyte solution, and DO calibration accessories are available separately. See our calibration solutions and accessories range.

For DO measurement alongside conductivity/salinity and up to three parameters simultaneously, see the LAQUA WQ-300 Series multiparameter meters. For comprehensive field monitoring including turbidity, depth, and GPS, see the HORIBA U-50 Series.

Also available:

• All portable water quality meters
• Calibration solutions and accessories
• LAQUA DO210/DO220 instruction manuals and brochures
• Contact Australian Scientific for technical support or volume pricing