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MQ-650: ePAR Underwater Meter

Make: Apogee                                      Model: MQ-650
✅ The MQ-650 ePAR meter is designed for underwater extended PAR measurements (400-750 nm).
✅ Measurand: Photosynthetically active radiation(PAR).
✅ Sensor Type: Blue-enhanced silicon photodiode
✅ Signal Output: UART protocol and requires the AC-100 to convert from UART to USB
✅ Supplied With: 2 m Cable, Factory test/ Calibration Certificates.

MQ-650: ePAR Underwater Meter:

The MQ-650 ePAR meter is designed for underwater extended PAR measurements (400–750 nm) and already applies the sensor’s immersion effect correction factor to the meter readings through firmware. The meter provides excellent measurements under all light sources, including LEDs. The meter consists of a waterproof quantum sensor attached via a waterproof cable to a handheld meter.

The waterproof sensor incorporates a blue-enhanced silicon photodiode and custom optical filters with a rugged, anodized aluminum body with an acrylic diffuser. The underwater quantum sensor is typically used in saltwater aquariums where corals are grown. Note: The handheld meter is not waterproof; only the sensor and cable are waterproof.

The meter can record an integrated daily total in mol m-2 d-1 and has a sample and log mode. Sample mode will record up to 99 manual measurements. Log mode will turn the meter on and off to make a measurement every 30 seconds. The meter will average the sixty 30-second measurements every 30 minutes and store the averaged value in memory. The meter can store up to 99 averages; once full, it will start to overwrite the oldest measurement with new ones.

An integrated daily total will be recorded from the 48 averaged measurements (making a 24-hour period). Sample and log measurements can be reviewed on the LCD display or by downloading the data to a computer; however, the integrated daily total can only be viewed by downloading the data to a computer. Downloading data to a computer requires the AC-100 communication cable (a standard USB cable will not work) and Apogee AMS software.

Apogee Instruments MQ-650 meters consist of a handheld meter and a dedicated sensor that is connected by cable to an anodized aluminum housing. SQ-600 series ePAR sensors consist of a cast acrylic diffuser (filter), photodiode, signal processing circuitry mounted in an anodized aluminum housing, and are potted solid with no internal air space. MQ series ePAR meters provide a real-time PFD reading on the LCD display, that determine the radiation incident on a planar surface (does not have to be horizontal), where the radiation emanates from all angles of a hemisphere. MQ series ePAR meters include manual and automatic data logging features for making spot-check measurements or calculating daily light integral (DLI).

Application and features of MQ-650: ePAR Underwater Meter:



✅ Applied to plant photosynthesis research, vegetation index research, etc.
✅ Greenhouse Monitoring
✅ Agricultural production
✅ Waterproof sensor and cable
✅ Anodized aluminum body with acrylic diffuser
✅ Accurate underwater measurements for all light




General Specification



180 g


Meter Dimensions : 126 mm length, 70 mm width, 24 mm depth
Sensor Dimensions : 30.5 mm diameter, 37 mm height

Measurement Range

0 to 4000 μmol m⁻² s⁻¹

Operating Temperature

0 to 50 C; less than 90 % non-condensing relative humidity up to 30 C; less than 70 % non-condensing relativity
humidity from 30 to 50 C; separate sensors can be submerged in water up to depth of 30 m

Temperature Response

-0.11 ± 0.04 % per C

Cable Length

2 m of shielded, twisted-pair wire; additional cable available; TPR jacket

Field Of VIew


Protection Level


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