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Measure PAR to ensure proper light levels for underwater photosynthesis.

Photosynthetic radiation is essential for the growth of the photosynthetic organisms such as corals. The wavelegth range from 400-700 nm is called PAR (Photosynthetically Active Radiation) or PPFD (Photosynthetic Photon Flux Density). Apogee quantum sensors are calibrated to measure th number of photons of light across this range. 

Original Apogee Quantum Sensor

The original Apogee quantum meters and sensors (with the black sensor head) are lower-cost options that are excellent for all light sources, except for most LEDs, where post-measurement correction factors need to be applied to achieve accurate readings.

  Full Spectrum Quantum Sensor

The new, MQ-500, Full Spectrum quantum meter (with the gold sensor head) features an improved detector that provides excellent measurements under all light sources, including LEDs, right out of the box.


Click for full screen    About Dr. Bruce Bugbee

Click for full screen    About Dr. Bruce Bugbee


Apogee Quantum Meters and sensors accurately measure an aquariums range of PAR (Photosynthetically Active Radiation) to give a better understanding of where to place aquatic specimen for optimal health. Measuring PAR can assist in lighting congiguration, tank arrangement, lighting malfuntions, and bulb replacement. The original Apogee Quantum sensor and meter (black head) are excellent for all light sources except most LEDs, where post-measurement correction factors need to be applied to achive accurate readings. The Full Spectrum Quantum meter (gold head) is ideal for use under all light sources, including LEDs, right out of the box.

How It Works
To ensure an aquarium specimen is receiving proper light, or photons, aquarium lighting can be tested for quantum or PAR outputs. PAR is the energy source required for photosynthesis, created by photons in the wavelengths of 400 to 700 nm, and can be measured from both sunlight and electric lighting sources. The energy source, PAR, is expressed in Photosynthetic Photon Flux, PPF, units µmol m-2 s-1.

Ideal for Underwater Use
Apogee Quantum Meters an USB Quantum Sensor have a waterproof sensor head. The sensor head is pottoed solid to seal it completely and ensure it hs no hollow cavaties for water to penetrate and cause measuremt errors.

Spectral Response
The Original quantum meter has a spectral range of 410 to 655 nm. The Full Spectrum quantum meter has a spectral range of 389 to 692 nm ± 5 nm. The improved spectral response increases the accuracy of LED measurements. The spectral responses can be be seen in the graph below (click to enlarge).
Original & Full Spectrum Quantum Sensor Spectral Response.

Datalogging Capabilites
The meters (MQ-200 and MQ-500) include datalogging capability and can store up to 99 manually recorded measurements. In automatic mode, measurements are made every 30 seconds and averages are stored every 30 minutes. Daily totals are also calculated for the past 99 days. The USB sensor (SQ-420) has an internal memory capable of storing 10,000 user-specified periodic measurements that can be downloaded to a computer.

Sensors are available with several outputs including: USB, pigtail leads to be connected with a voltmeter*, or with a handheld meter.
*PAR readings can be made using a stand-alone quantum sensor head, SQ-100 or SQ-500 series, with a high-quality voltmeter. To use the voltmeter connect the positive lead of the voltmeter to the red wire of the SQ and the negative lead of the voltmeter to the black wire of the SQ.
For the SQ-100 Series: To get the unit µmol m-2 s-1 multiply the mV reading by 5.0. Voltmeters with mV setting attain the best resolution.
For the SQ-500 Series: .To get the unit µmol m-2 s-1 multiply the mV reading by 100.0. Voltmeters with mV setting attain the best resolution.

Warranty and Support
All Apogee products are backed by an industry-leading four year warranty and outstanding customer support.


spec sheets
Spec Sheets




software download
Software Downloads



deep red leds The MQ-200 is often used by reef keepers to measure the PAR output of their electric lights to ensure proper specimen health.
Additional Information

The reef tank lighting market has recently grown exponentially with hundreds of lighting options now available, due to the increased popularity of reefkeeping. Unfortunately, all types of electric lights have a unique spectrum, and therefore also yield a unique set of spectral errors when measured by any commercially available PAR meter. In response to emerging electric lighting technologies, Apogee has done extensive research to help customers make accurate PAR readings with their MQ-200, wich can be found at this link Correcting for Spectral Errors of Common Electric Lights (MQ-200).

PAR requirements of coral varies greatly due to different depths and water conditions they naturally exist in. Each tank setup requires a unique type, intensity, and duration of light, which can be determined easily using the Apogee Instruments Quantum Meter and USB Sensor. Further information to determine aquatic specimen health can be found by asking a professional aquarist, becoming involved in a local reef club, through articles such as Photosynthesis and Photoadaptation by Sanjay Joshi, and through videos of our MQ-200 meter in action.

Apogee Quantum Sensors are recommended and sold by some of the biggest names in the aquarium industry:

Aquarium Specialty, Bulk Reef Supply, Premium Aquatics, Vivid Aquariums, Orange County Aquarium Supply