Experiment completed. A number of months ago I posted a question as to the difference between MH HQI 14000K and 20000K bulbs. The feedback from this forum was that the 14 had more PAR and therefor more beneficial for coral. I decided to test that theory and can now, without a doubt, support that opinion. I will spare you a lengthy thread but sufice to say after switching back to the 14000K bulb yesterday I note a definite improvement in the health of my coral. Yes, 1 day later! This after running the 20000K bulb for 6 weeks after running the 14K bulb for the same time period. Although the 20 gives off a superior light to enhance the green pigments the 14 has what my corals need and love.