Apogee Instruments PAR meters are the tool of choice for cost-effective, scientific-grade measurement of underwater PAR levels. Accurate tank PAR mapping, daily light integral measurements, and the adjusting of photosynthetic radiation levels to mimic nature are all critical to specimen health. Apogee offers three different underwater calibrated meters at three different price points. The basic MQ-210X features our original X detector that is excellent for broadband light sources. The researchgrade MQ-510 features an improved detector excellent for all light sources, including LEDs, and matches LI-COR and Kipp & Zonen PAR sensors in accuracy while costing much less. The cutting-edge MQ-650 measures the newly confirmed far-red extended (ePAR) photosynthetic wavelengths (400-750 nm).