Agreed, if I plan to have zoanthids and mushrooms in my tank and I physically see frags growing on the bottom what need do I have for numbers?Don't flame me, but I'm going to play devil's advocate. If your corals are thriving, what difference does it make what your PAR values are? I can see the usefulness when setting up a new tank or perhaps changing lights, but in an established healthy tank, I question the need.
I see a lot of people in this hobby getting caught up in chasing numbers to the overall detriment of their tank, especially with regard to PO4/NO3. Above all else, corals crave consistency. I prefer to let results guide my husbandry and not numbers.