Just read in RC. Someone pointed out a link.
http://hennings-miniriff.jimdo.com/vortrag-sindelfingen-2013/messungen/verluste-von-led-modulen/
Ophek Atlantik loses 80% in 8mths!?!
Led may last but not the spectrum n par. Not sure how accurate are these studies and do the corals response negatively to this. So planning to monitor the kessils based on the response of the corals.