Grow Lights Australia
Well-Known Member
Hi shotnva777 these types of LEDs can be confusing because you do not always get what the Chinese manufacturers say you are getting! Looking at the advertised spectrum compared to your lights I would want a proper spectograph reading see what the spectrum is really like but I will try to answer your questions anyway.
The "sunlight" LEDs appear to be typical 3500K CRI80 2835 diodes which are nothing special but CRI80 3500K is a good alround colour temperature for growing. The UV LEDs are not very powerful considering the number of them so I would say they are not very efficient. But they would be better than nothing. The "purple" LEDs are confusing because they look like phosphor-coated red diodes which are made by using a 450nm blue pump LED die and then applying a red phosphor to it that spreads the red peaks from 660nm into the far red range. We call these "PC Reds" and we sell them ourselves. They are less efficient but they can add valuable far red to the spectrum. If they are PC Red then that might explain why the Chinese call them "purple" because they convert blue light to red. Perhaps that is their logic but they are a red diode not a purple diode.
We put our full spectrum on one channel because we believe it is not only more efficient and less complex which keeps down costs but because we believe in enhancing the spectrum for the entire grow to maximise growth. There are benefits to UVA and far red throughout the plant cycle and this is easily explained when you consider there is more UV during the vegetative phase outside under the sun in late spring and summer than there is during bloom when it is late autumn. There is also a lot more far red light in sunlight than any LED. Sunlight is 25% far red and seems to work well with the UV side of the spectrum to enhance growth but to reduce internodal stretch from shade avoidance which you would expect when increasing the red to far red ratio. Plants don't tend to stretch outdoors even though there is a large amount of far red and we believe this is due to the addition of UV at the other end of the spectrum.
If it were up to us we would suggest using all LEDs at once throughout the grow. You may need to dim the entire fixture or hang it higher during veg as you will not need as much light intensity during 18 or 20 hours of lights on compared to 12 hours during flowering. Running both channels at the same time will be less efficient because the PC Red and UV diodes are not as efficient as the 3500K diodes but the spectrum would be more complete.
