FIGURE 2. Spectral energy distribution (S.E.D.) at water surface (dotted line) ; energy
detected through wide and narrow band-pass interference filters (horizontal bars). S.E.D.
curve was interpolated, amounting to approximately 3.7 kilolux as the integrated area from 375
to 725 nanometers. For combined source, using 40 watts Gro-lux and 40 watts warm white
(fluorescent). Details in text.