This has been an on again/off again project. I used a Seneye 'Reef' device to measure CCT (in Kelvin) and Photosynthetically Usable Radiation for these light sources:
Sunlight - slightly overcast February day at noon, Atlanta, Georgia. CCT = ~6,200K.
Iwasaki 400-watt 'daylight' metal halide lamp. Often proposed to the 'best' lighting source for coral growth by some of the old-timers. CCT =6130K. Lamp burned in 100 hours and warmed up for 20 minutes.
Blue LED (452nm) Orphek Blue Sky fixture. CCT exceeds limit of device.
Aqua LED (496nm) Orphek Blue Sky fixture. CCT = ~13,000K. This light is absorbed by the accessory photopigment peridinin.
Results suggest the blue LED is about 22% more efficient than the metal halide lamp, lending some evidence that LEDs are more powerful photosynthetically.
Sunlight - slightly overcast February day at noon, Atlanta, Georgia. CCT = ~6,200K.
Iwasaki 400-watt 'daylight' metal halide lamp. Often proposed to the 'best' lighting source for coral growth by some of the old-timers. CCT =6130K. Lamp burned in 100 hours and warmed up for 20 minutes.
Blue LED (452nm) Orphek Blue Sky fixture. CCT exceeds limit of device.
Aqua LED (496nm) Orphek Blue Sky fixture. CCT = ~13,000K. This light is absorbed by the accessory photopigment peridinin.
Results suggest the blue LED is about 22% more efficient than the metal halide lamp, lending some evidence that LEDs are more powerful photosynthetically.