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MQ-650: ePAR Underwater Meter

Make:  Apogee                                      Model:  MQ-650
✅Sensor heads are fully epoxy potted to be completely waterproof.
✅ Sensor readings are adjusted in firmware to correct for the immersion effect.
✅ Long-term non-stability .
✅ The meter records up to 99 measurements in logging mode.
✅ Data can be downloaded to calculate DLI.

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 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 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.

The meter has a sample and log mode, and will record an integrated daily total in mol m-2 d-1. Sample mode will record up to 99 manual measurements. Log mode will power the meter on/off to make a measurement every 30 seconds. Every 30 minutes the meter will average the sixty 30 second measurements and record the averaged value to 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 hr 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 ApogeeAMS software.





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