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

How It Works
PAR (Photosynthetically Active Radiation) is the energy source required for photosynthesis, created by photons in the wavelengths of 400 to 700nm. The energy source, PAR, is expressed in Photosynthetic Photon Flux Density (PPFD) units µmol m-2 s-1. PAR can be measured from both sunlight and electric light sources to ensure corals are receiving proper light or photons for optimal health. PAR requirements of coral varies greatly due to different depths and water conditions they naturally exist in. Information on specific coral PAR requirements can be found by asking a professional aquarist becoming involved in a local reef club and through articles such as Photosynthesis and Photoadaptation by Sanjay Joshi. Apogee quantum/PAR meters and sensors accurately measure an aquariums range of PAR (Photosynthetically Active Radiation) to give a better understanding of aquarium lighting, for more details click here.

Original Sensor
A lower-cost option that is excellent for all light sources, except most LEDs, where post-measurement correction factors need to be applied to achieve accurate readings. The original quantum sensor has a spectral range of 410 to 655 nm seen in graph to the right. The sensor is available attached to a hand-held meter that provides a digital readout (MQ-200) and in multiple analog outputs to be used with a datalogger or voltmeter.

Spectral Response

Full-spectrum Sensor
Features an improved detector that provides excellent measurements under all light sources, including LEDs, right out of the box. The full-spectrum quantum sensor has a spectral range of 389 to 692 nm ± 5 nm seen in graph to the left. The sensor is available attached to a hand-held meter that provides a digital readout (MQ-500), with USB communication and custom software (SQ-520), and in multiple analog outputs to be used with a datalogger or voltmeter.

Datalogging Capabilities
The MQ-200 and MQ-500 meters record 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. The SQ-520 USB sensor has internal memory capable of storing 10,000 user-specified periodic measurements that can be downloaded to a computer.

Ideal for Underwater Use
All Apogee PAR/Quantum sensors have a waterproof sensor head. Sensor heads are potted solid for a complete seal and to ensure it has no hollow cavities for water to penetrate and cause measurement errors. Apogee quantum sensors can be used to make absolute PPFD (PAR) measurements underwater by applying geometric and immersion effect correction factors using Apogee's Underwater PAR Calculator. For details on making underwater measurements and to download the calculator, please refer to Underwater PAR Measurements.

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

   

Need help choosing a sensor?

  Technical Information
Technical Information
Find software, articles, manuals, FAQs, technical support, and more.
 
 
What type of Quantum Sensor do I need?
 
Apogee Instruments produces two types of quantum sensors.

The Original Quantum Sensor (SQ-100, SQ-200, SQ-300, and SQ-400 Series) have a spectral range of 410 to 655 nm. The Original Quantum Sensor works great for most single light, non-LED, and sun applications.

The Full-spectrum Quantum Senor (SQ-500 Series) has a spectral range of 389 to 692 ± 5 nm. The Full-spectrum quantum sensor is the best option for LED and multiple light applications.

Once sensor type is determined, you will need to decide what output is needed to determine the sensor model number. This is usually dependent on the type of controller/logger you have.

 
Which Original Quantum Sensor model do I need?
 
All Original Quantum Sensors (SQ-100, SQ-200, SQ-300, and SQ-400 series) use the same detector. The model number you need depends on which output is compatible with your datalogger and if you are measuring a sun or electric light source. Model numbers are listed below with their output and calibration:
SQ-110 0 to 800 mV 0 to 4000 µmol m-2 s-1 Sunlight Calibration
*To use a voltmeter connect the positive lead of the voltmeter to the red wire of the SQ and negative lead of the voltmeter to the black wire of the SQ. To get the unit µmol m-2 s-1 multiply the mV reading by 5.0. Voltmeters with mV setting attain the resolution.
SQ-120 0 to 8000 mV 0 to 4000 µmol m-2 s-1 Electric light calibration
*To use a voltmeter connect the positive lead of the voltmeter to the red wire of the SQ and negative lead of the voltmeter to the black wire of the SQ. To get the unit µmol m-2 s-1 multiply the mV reading by 5.0. Voltmeters with mV setting attain the resolution.
MQ-200 Sensor attached to a handheld meter with digital readout Electric and sunlight calibration
 
Which Full-spectrum Quantum Sensor model do I need?
 
All Full-spectrum Quantum Sensors (SQ-500 series) use the same detector. The model number you need depends on which output is compatible with your datalogger. Model numbers are listed below with their output:
SQ-500 0 to 40 mV 0 to 4000 µmol m-2 s-1
*To use a voltmeter connect the positive lead of the voltmeter to the red wire of the SQ and negative lead of the voltmeter to the black wire of the SQ. To get the unit µmol m-2 s-1 multiply the mV reading by 100.0. Voltmeters with mV setting attain the resolution.
SQ-520 USB/software 0 to 4000 µmol m-2 s-1
MQ-500 Sensor attached to a handheld meter with digital readout 0 to 4000 µmol m-2 s-1
 
Can I use a voltmeter wih my sensor?
 
Voltmeters can be used with the SQ-110, SQ-120, or SQ-500.

To use a voltmeter connect the positive lead of the voltmeter to the red wire of the SQ and negative lead of the voltmeter to the black wire of the SQ. Voltmeters with mV setting attain the best resolution.

SQ-100 series: To get the unit µmol m-2 s-1 multiply the mV reading by 5.0.

SQ-500 series: To get the unit µmol m-2 s-1 multiply the mV reading by 5.0.

 
How do I correct for spectral errors of my Original Quantum Sensor?
 
Apogee has done extensive research to help custometers make acurate PAR readings, which can be found here.
 
What quantum sensor should I purchase for my aquarium?
 
You should purchase the quantum sensor that matches your aquarium light source the closest. We recommend the MQ-200 for supplemental electric lighting and sunlight. We recommend the MQ-500 or SQ-520 for LED lights. When using Apogee quantum sensors underwater, please refer to Underwater PAR Measurements.
 
Are Apogee quantum meters waterproof?
 
No, the meter is only splash resistant and should never be submerged. However, the sensor heads and cables on the MQ-200, MQ-300, and MQ-500 series are waterproof and can be used underwater. If Apogee quantum sensors are used underwater, please refer to Underwater PAR Measurements
 

spec sheets
Specification Sheets

 

 


Photos

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.

 


Videos

Why do I need a PAR-Quantum Meter?

 

In-depth Look at PAR-Quantum Meters


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

Aquarium Specialty, Bulk Reef Supply, Premium Aquatics

 

Models


For complete quantum sensor selection visit Original Quantum Sensor and Full-spectrum Quantum Sensor