High Energy Visible (HEV) light refers to the part of the spectrum from 380-530nm, which includes our beloved blue and royal blue LEDs as well as the violet, indigo, cyan and near-UV LEDs which are not yet widely used. With many reefers currently running heavily blue lighted aquariums and the adoption of LEDs and their superpowers in the blue end of the spectrum, we’ve been quietly concerned about the potential for us to overdose our corals with HEV light.
HEV light has already been implicated as one of the causes of macular degeneration (vision loss) in people. In addition to urging you to use caution when you are near high power blue or purple LEDs, we should also consider how HEV light can affect our reef tanks. We already know that many of our photosynthetic reef animals are sensitive to too much red light, too much light and lights that are on for too long. We also know that photosynthetic pigments get tweaked for higher performance towards the blue end of the spectrum due to the attenuation of sunlight as it penetrates seawater. Therefore it is not a big leap to consider that huge quantities of blue light from multiple emission peaks could be enough to cause some injury to our photosynthetic reef animals.
In working with a variety of blue LED lights over corals, we can at least say that corals react to blue light from LEDs in unexpected ways for the given measured PAR value, and the perceived brightness of the light by our eyes. Hit us up in the comments if you’ve experienced unexpected results using blue LED lights over your corals; we’re particularly interested in hearing from the CoralSky SL2 and blue Ecoxotic LED cannon users since these are some of the highest density blue LED lights currently in the reefing hobby.