[jcltok]

I think this where the confusion lies:


"Radiance flux (ФЄ) is the energy per unit time (dQ/dt) that is radiated from a source with the range of .01 to 1000 μm4, which includes the visible, infra-red and U.V regions. A radiant flux of 1 watt means that the source produces 1 joule of energy per second."

So radiance flux measure a WIDE range of energy that is not good to or useful to coral photosynthesis. I have no interest in the visual aspects of light when I speak of lumen - I focus on the photosynthetic range which also happens to be 400nm to 700nm.

PAR meters - "Quantum sensors measure light energy at the specific wavelengths plants actually use for photosynthesis. All quantum meters measure Photosynthetic Photon Flux (PPF) as µmol 2m-s for Photosynthetically Active Radiation (PAR) in the range of 400 to 700 nm. The meter approximates radiation between 400 and 700 nanometers(PAR) as umol m2-s."

Mind that you can fool a PAR meter by loading on one wavelength. It is unethical but it is being done.

I hope this helps the discussion and explains why I suggest PAR and good Lumen/Lux meters for measuring what light is getting to the water. To me what is being radiated is not important if by the time it gets to the water, it is minimal amounts of energy - there are so many variables that radiance cannot be applied consistently (2 units produce the same radiance, but one is hung 12 inches above he water and the other is hung 18 inches - same amount of radiance but different impact at the water).

What is important is what is happening at the water. Let me also clarify that I do believe different corals need different PAR and lumen - I just haven't seen academic research showing the PAR requirements for each type coral.

I am sure Dana Riddle lives up to his reputation and would urge him to publish in the academic world so we can all see his methodology and analysis. With his experiments, Marine Biology would gain much.

Regards,