new test light

[daveb]

so also got a new led bulb to replace the CFL in an old hydrofarm Agrobrite GROW-FLCO125D hanging light. new bulb is rated 60watt draw the replacement bulb in CFL is $52 to $100 usd depends where buy it from. the original cfl was rated at 125 watt 6400 Kelvin and had the large E39 base i believe they rated these from 500 to 7000 lumens visible light.

then new bulb is what is refered to as a corn cob it has the E39 base 60watt draw and at 20 inches from the bulb/reflector housing registers 10900 lumens and cost #16.99 usd

the light over powered the camera on phone so pardon the quality

 

[Berkeloid]

Is it a full spectrum light? Often LED lights have fairly narrow peaks around the red, green and blue parts of the spectrum so it seems white to human eyes, but they don't provide as much usable light to plants.

I mean CFLs have a bit of a reputation for the same, so I don't imagine you'll be any worse off, I'm just curious.

I've seen Ikea sell special LED grow lamps which emit a more purple light, because they produce a lot of red and blue, but very little green (since most plants reflect green anyway and the energy used to produce the green light would go to waste), so I've often wondered what kind of a difference there actually is between white and red/blue lights as far as plant growth goes.

 

[daveb]

full specturm but primary band width in the upper range to duplicate the 6500 kelvin and down of the CFL

ive actually build a few light panels for my hydroponics also

 

[daveb]

soon as i get time i will run better meter but visual with a 400 - 700 spectroscope to see where the peaks are i have linked a shoot through the lens, for the use i plant to use it for i want the push more in the 6000 to 6500 anyways for vegetative growth. and yes reason you lights as some refer to them as plurple they pin point specific spectrums light red blue and without the reactive coating the will flash out the visible white light

posetd actual spectroscope shot of new light with text to indicate key points. A good splash in the blue light 6000 to 6500 where I was looking for plus good but not aggressive red spectrum.
Meter reading at .5 meter above surface just slight over 1 sq meter illuminated gave a reading 11200 lux / 7.61 DLI on 10 light on, this was open without and reflective sides so the total number would increase




light range and affects

 

[Berkeloid]

Wow that's really interesting! I never realised plants could make that much use of the upper UV spectrum. Very interesting too to confirm the LEDs are full spectrum.

 

[daveb]

Wow that's really interesting! I never realised plants could make that much use of the upper UV spectrum. Very interesting too to confirm the LEDs are full spectrum.

the issues here is though the red to blue ratios this bulb is great as a fill in to give some fill in one of my systems that is lower on blue spectrum. ratios have been tested range from .5 to 5 and up to 10 in sets i tried so as example when i refer to .5 ratio 460nm for blue and 660nm for red spectrum and twice an many lumen lux or ppfd how ever you decided to measure of blue versus red . Where as 5 ratio 5 times as much red as compared to blue. As the ration increased so did the yields on leafy greens herbs, and the higher the red the more responsive plants are to bloom so higher red spectrum for tomatoes pepper strawberries to trigger them to set fruit.

Optimum for lettuces tends to stay in the 3:1 r/b this does multiple things higher red increase fresh and dry weight so there is a marked increase of actual plant material , and higher red spectrum increases the antioxidant level of plants we consume. blue red balance increases flavors and fruit yield so this is why the sun makes for such good vegetables, morning / evening the light is shifted more to higher amount of red, as mid day come around more direct sun so a the red levels drop down also the reason behind one light panels i am designing the will shift the light mix and intensity to duplicate a natural transition of lights spectrum during day.

One additional thing UV and near infrared penetration forest and foliage canopy more then do some of the other spectrums and some receptors on leaves are specific to absorb these.

here is a simple overlay of two recorded graph of light during day 6 am and 6 pm are very closer to identical not the marked increase in 640 to 940nm range