Self-made LED panel general discussion

R/B leds miss what makes hps so good- the mid band


The following is copied from The Lurker (TL)

This is a Eye Hortilux HPS vs. Photosynthetic Absorption Spectra Curve.






I'm glad we've finally gotten some good studies on green light over the past several years, as has been mentioned previously (link) by a few of us.

While 'every lumen (or rather, PPFD) is sacred', I'm of the camp that would prefer a higher level of (adjustable) full-intensity, multi-spectrum (i.e. 'white') light incorporated into the main fixture, for that very reason.

And with the recent increases in the efficiency of neutral whites, there's no reason why you can't get perfectly good results with just a two-channel, adjustable led fixture (neutral white, and red), supplementing with the aforementioned only as needed.





(note: neutral white I called 'normal white' here for some reason. Wonder what I was smokin' at the time...<whistles>)

As one can see, the CREE Neutral White (I call it 'Goldilocks', because it's almost 'just right' ) has a RSPD that still allows nearly ~25% of its total power in the blue range (and plants only really 'need' ~8-10%), and more that 1/3 of which (i.e. the area under the curve) is over ~580nm or so (which has a Photosynthetic RS of over 90%!) - which is much better than even your typical 'Enhanced HPS'.


So like Gastanker, I too thing these whites are very SEXY

Damn I wish TL would lurk a little less and chime in more..........SO who's gonna be the first to run(build) a cree xpe neutral white/630/660 only panel???love to see that, sounds very promising on paper.........YES very sexy indeed

Wish Hilo would update his white/red panel grow..........happy growing fellas

edit: hey Pet where did you get that info that cannabis only needs "8-10%" 400+nm during veg?????

Thank you for contributing
One remark though, you can clearly see it isn't exact science as the two photosynthetic curves (from the first picture and from the second one) are not the same at all. And for which plants are they anyway ? as I remarked on the other topic, for instance, tomatoes and lettuce don't respond the same way at all to different light spectrums. So far, I've never seen anything scientifically supporting the fact that MJ can really benefit from light in the middle of the spectrum. Results with high quality red & blue LEDs are already very satisfying and quite superior to HPS.

It seems to be very difficult to find objective information on this subject as most discussions are flooded by either ignorant individuals or people with a commercial interest in the debate. I'm glad to have a rich discussion here

yes but, cree warm whites are important too; I mean if you are keen on IR, without using IR you get real good IR from warm whites ! Plants can grow without IR, that's proven, but it seems to add on roots structure and flowering time (it shortens that)

I think IR is an important ingrediant that isn't being used enough in most panels. I supplement with extra IR spotlights and have found them to be of value. Makes for bigger/denser flowers and supposed to help promote germination in seedlings but I haven't tested that part yet.

Originally Posted by PSUAGRO.

Damn I wish TL would lurk a little less and chime in more..........SO who's gonna be the first to run(build) a cree xpe neutral white/630/660 only panel???love to see that, sounds very promising on paper.........YES very sexy indeed

Wish Hilo would update his white/red panel grow..........happy growing fellas

edit: hey Pet where did you get that info that cannabis only needs "8-10%" 400+nm during veg?????

from da man, TL Where else?

RapidLED kits are based around Cree Whites. Great for small closet growers/vegging/cloning, or anyone with $$$

Originally Posted by jubiare

yes but, cree warm whites are important too; I mean if you are keen on IR, without using IR you get real good IR from warm whites ! Plants can grow without IR, that's proven, but it seems to add on roots structure and flowering time (it shortens that)

Yes, light in the 740nm range seems to be very beneficial, but, as we can see from the radiant curve of the Cree XP-E warm white, only less than 4% of the total light is emitted above 700 nanometers. This means that putting independent far red LEDs seems to be more efficient to cover that part of the spectrum.

Originally Posted by puffenuff

I think IR is an important ingrediant that isn't being used enough in most panels. I supplement with extra IR spotlights and have found them to be of value. Makes for bigger/denser flowers and supposed to help promote germination in seedlings but I haven't tested that part yet.

Yes, but what I learned from TL is that you only need it for a short period immediately after lights out, so it would need to be separate fixture and on a separate timer. Problem is finding small wattage IR bulbs. Reptile lights has one with a remote ballast. Now all that's needed is a cheap light mover. Alas, this won't work with my 8 bulb Quantum BB. Next time I would get 2 @ 4 bulb, unless I bite on some RapidLEDs