Designed by world-renowned crop physiologist, Bruce Bugbee, PhD, the Apogee MQ-210X "original" quantum meter features Apogee's older and more economical photodetector that is excellent for measuring photosynthetically active radiation (PAR) accurately under sunlight, metal halide, and high-pressure sodium lights. For measuring other light sources, including LEDs, we recommend using our newer full-spectrum or ePAR sensors.

Measuring the PAR levels of your grow lights is one of the most critical measurements in the precision growing of plants and other photosynthetic organisms in greenhouses, growth chambers, farms, gardens, and aquariums. Our underwater original quantum meters are specifically designed to measure the intensity of sunlight, MH, and HPS lights underwater for biological, chemical, and physical processes in natural waters and aquariums.

Underwater PAR measurements can read low when a sensor is calibrated for air. This applies an immersion effect correction factor to get accurate measurements underwater by combining the intensity of all photons between 400-700 nm under sunlight, MH, and HPS lights to give a single PAR reading within 5 % uncertainty. Unlike hobby-grade PAR meters that may be accurate when new, but quickly lose calibration, our meters are stable with a drift rate of less than 2% per year.