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Enabling better global research outcomes in soil, plant & environmental monitoring.

MQ-510 Full Spectrum Underwater Quantum Meter

The MQ-510 quantum meter is designed for underwater PAR measurements and already applies the sensor's immersion effect correction factor to the meter readings through firmware. The meter consists of a waterproof quantum sensor attached via waterproof cable to a handheld meter. The waterproof sensor incorporates a blue-enhanced silicon photodiode and custom optical filters with a rugged, anodised aluminium body with acrylic diffuser. The underwater quantum sensor is typically used in salt water aquariums where corals are grown.

Note: The handheld meter is not waterproof, only the sensor and cable are waterproof.

Ready for Underwater Use
The MQ-510 has the immersion effect correction factor pre-programmed in the meter firmware allowing you to make excellent underwater measurements right out of the box.

Waterproof Sensor
The meter features a waterproof sensor head that is potted solid for a complete seal, and to ensure it has no hollow cavities for water to penetrate and cause measurement errors.

Refined Spectral Response
Improved detector and custom optics provide excellent measurements under all light sources, including LEDs.
The full-spectrum quantum sensor has a spectral range of 389 to 692nm, ± 5nm.

Accurate, Stable Measurements
Calibration in controlled laboratory conditions is traceable to an NIST lamp. Quantum sensors are cosine-corrected, with directional errors less than ± 5% at a solar zenith angle of 75°. Long-term non-stability determined from multiple replicate quantum sensors in accelerated aging tests and field conditions is less than 2% per year.

Datalogging Capabilities
The meter records up to 99 manual measurements. In logging mode the meter will make a measurement every 30 seconds. Every 30 minutes the meter will average the sixty 30 second measurements and record the averaged value. The meter can store up to 99 averages.

Calibration Traceability

Apogee Instruments SQ-500 series quantum sensors are calibrated through side-by-side comparison to the mean of four Apogee model SQ-500 transfer standard quantum sensors under high output T5 cool white fluorescent lamps. The transfer standard quantum sensors are calibrated through side-by-side comparison to the mean of at least three LI-COR model LI-190R reference quantum sensors under high output T5 cool white fluorescent lamps. The reference quantum sensors are recalibrated on a biannual schedule with a LI-COR model 1800-02 and quartz halogen lamp that are traceable to the National Institute of Standards and Technology (NIST).

Cosine Response

MQ-510 G1


Mean cosine response of seven Apogee MQ-510 quantum sensors. Cosine response measurements were made on the rooftop of the Apogee building in Logan, UT. Cosine response was calculated as the relative difference of MQ-510 quantum sensors from the mean of replicate reference quantum sensors (LI-COR models LI-190 and LI-190R, Kipp & Zonen model PQS 1). The red data are AM measurements; the green data are PM measurements.

Spectral Response

MQ-510 G2

Mean spectral response measurements of six replicate Apogee MQ-210 and MQ-5100 series quantum sensors. Spectral response measurements were made at 10 nm increments across a wavelength range of 300 to 800 nm in a monochromator with an attached electric light source. Measured spectral data from each quantum sensor were normalised by the measured spectral response of the monochromator/electric light combination, which was measured with a spectroradiometer.


Spectral Errors of Commercial Quantum Sensors

Radiation Source Apogee
Kipp & Zonen
Sun (Clear Sky) -2.2 0.0 -0.4 -1.0
Sun (Cloudy Sky) -1.7 1.4 -0.2 -1.3
Sun (Reflected from Deciduous Leaves) -2.0 4.9 -0.8 1.1
Sun (Transmitted below Wheat Canopy) -1.1 6.4 -0.1 -0.3
Cool White Fluorescent (T5) 0 0 0 0
Metal Halide 0.9 -3.7 0.2 -1.7
Ceramic Metal Halide -0.3 -6.0 0.4 -0.7
High Pressure Sodium 0.0 0.8 1.3 1.4
Red/Blue LED (16% 444 nm, 84% 667 nm peaks) -3.4 -65.3 3.5 -1.8
Red/White LED (6.5% 436 nm, 4.5% 531 nm, 89% 668 nm peaks) -3.0 -60.3 2.6 -1.7


Spectral errors are theoretical errors calculated from sensor spectral responses (Apogee SQ-100 and SQ-500 series shown in graph above) and spectral output of radiation sources (measured with a spectroradiometer). Only spectral errors are listed in the table. Calibration, cosine, and temperature error can also contribute to measurement error.

Calibration Uncertainty: ± 5%
Measurement Range: 0 to 4000 µmol m-2 s-1
Measurement Repeatability: Less than 0.05%
Long-term Drift (Non-stability): Less than 2% per year
Non-linearity: Less than 1% (up to 4000 µmol m-2 s-1)
Response Time: Less than 1 ms
Field of View: 180°
Spectral Range: 389 to 692nm, ± 5nm (wavelengths where response is greater than 50%)
Spectral Selectivity: Less than 10% from 412 to 682nm ± 5nm
Directional (Cosine) Error: Less than ± 5% at 75° zenith angle
Azimuth Error: Less than 0.5%
Tilt Error: Less than 0.5%
Temperature Response: -0.11 ± 0.04% C-1
Uncertainty in Daily Totals: Less than 5%
Detector: Blue-enhanced silicon photodiode
Housing: Anodised aluminium body with acrylic diffuser
IP Rating: IP68
Operating Environment: 0 to 50°C; less than 90% non-condensing relative humidity up to 30°C; less than 70% non-condensing relative humidity from 30 to 50°C; separate sensors can be submerged in water up to depths of 30m
Meter Dimensions: 126mm length; 70mm width; 24mm height
Sensor Dimensions: 24mm diameter; 37mm height
Mass: 180g
Cable: 2m of two conductor, shielded, twisted-pair wire; additional cable wire available; santoprene rubber jacket

MQ-510 Dimensions

  • AA-100: Protective Carrying Case
    Protective carrying case designed to transport and store Apogee meters, sensors, and accessories.
  • AM-320 Saltwater Submersible Sensor Wand
    This accessory incorporates a mounting fixture at the end of a 40 inch (102 cm) segmented fiberglass wand and is well-suited for fresh and saltwater use. The wand unscrews into three sections for easier storage and transport. All radiation sensors are compatible with the wand, which allows the user to place the sensor in hard to reach areas such as in aquarium tanks and greenhouses.