Light opinions?

I could be wrong but I think you’d want something presenting more blue spectrum than a 6.4k LED. Since you’re going for growth.

 

That's not near enough light for anything other than small seedlings.

 

Squeeze the sides of the globe to get the glue to release, they are tough, sometimes I slowly step on them. The globe will bend and elastically deform but the LED base won't, so by deforming the globe, it breaks the glue bond between the base and the globe. You'll get considerably more light with the globes off. I've used the same bulbs. They work great. 6500K is very blue. (5) 30W bulbs per (4) veg plants works well.

 

I think natural daylight is 7.5k and actinic blue is 20k. If it was for veg alone would using something with double digits spectrum be better ? Maybe not 20k but 10k?


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Daylight is around 5600K typically on the average.



Degrees K, or the Kelvin color temperature refers to how hot a black mass would have to heat up to in order to emit the various wavelengths described by the particular Kelvin color temp rating. When you heat up an iron rod it begins to glow. At first its dark red, then moves to red/orange, then to yellow where it melts. In each different stage there was a different temperature of the rod, and that's why it emitted different colors or CCTs (color temps). Degrees of Kelvin are the same thing as degrees of Celcius, the only difference is Celsius goes negative whereas Kelvin starts at 0.

0°C = 273°K, -1°C = 272°K, 10°C = 283°K, ect.

I wouldn't veg any higher than 6500K. The quantum efficacy drops for the same irradiance the higher in CCT you go, so it contributes to a lower photosythetic efficiency aside from the reduced action at higher energy WV's compared to lower energy WV's.

 

TBH I'm not exactly sure, but I'd venture a guess of ~20%? Without the globe the light shoots down, with the globe the light shoots out the sides ect as well as down, so if you're not in a tent, its wasted light, if you are in a tent (or by a reflective barrier) then it still is less efficient because the barrier doesn't reflect 100%, it also absorbs a bit.

 

Those have a good spectrum imo. The reflector saves it. Same thing as the globes,... HID and fluoro as well as other lights emit in 360°, so half the total light is shined to places that can't use it (same with globes). With the reflector, the half of the light that normally would be escaping is being reflected back down. The reflector absorbs some of the light, as well as the bulb itself when the light gets reflected back onto it. Because half of the light has to travel up, bounce off the reflector, and then back down, it has a farther distance to travel than the half of light that shoots straight down naturally. This can result in the reflected light being even further reduced in intensity ontop of the reflector losses (losses dependent on reflector design). The non LED lights are not very efficient, so they'll take more watts from the outlet to provide the same amount of light ontop of emitting in 360°, where half the total light is diminished in intensity from reflector losses as well as any extra spread from the increase in distance traveled. This is why everyone is so hot on LEDs. They emit all of their light in one direction, down, eliminating reflector losses ect, and they are also more efficient to begin with so its like a double whammy. The benefit that some of the older tech can have comes from the spectrum they produce, as well as if you need extra heat in your grow because maybe you live in a cold climate. Then less efficient lights are beneficial because they'll create more waste heat. CFL is much more efficient than incandescent, but less efficient than LED. I personally like the fluoro spectrum, and when you're vegging you're using less wattage anyways, so using a less efficient light is less noticeable when it comes to heat and operating cost. Not a bad idea to use both.

I'd stay under 30W/ft2, probably shoot for 20W/ft2 if using the LED, and up to 30W/ft2 with the CFL. Somewhere in between if blended.