He explained what PAR and PUR is. How to use a PAR meter and what range of PAR is useful for corals. Most corals don't need the high par values and that from 100 on to 600 PAR is what most corals can use. Also he touched on K or Kelvin ratings and that above 6000 K is not used by most coral, higher values than that are just to show off the corals but will, over time, cause loss of coral color. There in lies the trade off between brightness and usefulness. It was hard to hear some of what he said as he faced the screen most of the time and not out to us. He was very helpful and friendly. He also commented on the lack of an industry standard for light ratings. I hope that helps some.