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[Opie Yutts]

. People who designed these lamps are focusing only on the absorption spectrum of chlorophyll and it's a big mistake. RED and BLUE should compose 70% of the lamp spectrum, but providing some white light with a complete spectrum is also important.

I haven't read this anywhere else, but I believe you are correct. Been thinking the same thing. How did you come up with 70%?

Lumen is really a poor measure for the plant grow potential of a lamp.

Correct. Everyone cries Lumens! Lumens! But this is only what we see. You need to measure what plants see. This measurement is Radiant Flux, not Luminous Flux.