I'll chime in here with something. All of the LED grow light fixtures that you see on the market are almost exclusively 660nm red and 455nm blue. This is the red that corresponds to the Chlor. A peak and the blue that corresponds to the Chlor. B peak. So why mix them? If one were trying to hit both peaks, why wouldn't you throw in 630s and 430s as well? Simple. Money. Violet 420-430 LEDs have not been readily available at a good price point. RBs are a dime a dozen comparably.

However, as it is becoming apparent that the spectrum coming off T5HO/VHO actinic and MHs is excluded in most LED build (stock or DIY), people are noticing things that don't work the same. Hence the demand for Violet is rising and price is dropping as supply ramps up.

I for one will be re-visiting my "light experiment" and putting together some test scrubbers. In reality, the 660nm Red should be paired with 420-430nm Violet for hitting all of Chl A. BTW the Clh A is the primary wavelength put out by the sun, and the "B" bands (455 and 630) are used during sunrise and sunset. At least that's how I understand it.