CREE DIY Question

deakus

deakus

Member
Apologies in advance if repeating previous q's. I have searched but couldn't find a definitive answer.
Very,very new to d game!
Have small 2' x 2' grow with 2×CXA3050 (2700K), Seedling (indica)starting, to go in soon.Using 2" of perlite in base with coco on top in 5 gallon.
Thinking of supplementing set up with either another Cree 3070 or 3590.
I have 3 questions, given that using 2700k for whole grow period (will be using red 650nm leds for 15 mins at end of 12/12 days when i get there!).
1.Which Cree model would experienced diyers go for?
2.Which "bin"?
3.I saw on digikey the only 3590's they stock are "4-Step MacAdam Ellipse".....having Googled and searched on RIU....what does that mean? I.e. does it affect what I would do with them?
Any help welcomed!
 
gk skunky

gk skunky

Well-Known Member
I'd go with 3070. Here's all I know about the 2 vs 4 step.





2-step MacAdam ellipse — For applications where the white LEDs (or white LED fixtures) are placed side-by-side and are directly visible, or when these fixtures are used to illuminate an achromatic (white) scene. Accent lighting a white wall and lighting a white cove are some examples. (The chromaticity values of presently available T8F32 linear fluorescent lamps operated on electronic ballasts fall within 2-step MacAdam ellipses.)
4-step MacAdam ellipse — For applications where the white LEDs (or white LED fixtures) are not directly visible, or when these fixtures are used to illuminate a visually complex, multicolored scene. Lighting a display case and accent lighting multicolored objects or paintings are some examples.

http://en.m.wikipedia.org/wiki/MacAdam_ellipse

I think essentially it means 2 step are more constistant color wise and 4 step color varies more from diode to diode. Could be wrong though.

And curious why 660 only the last 15 minutes? I thought only 730-780nm far red initiators were to be used before lights out and right after.
 
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deakus

deakus

Member
Thanks both. Think i may go 3070 as suggested. Regarding red660nm...i read somewhere on here that this helps "switch the plant off/put it to sleep" much quicker (when in flowering). Im probably wrong...wouldn't be the 1st or last time!
Cheers
 
SupraSPL

SupraSPL

Well-Known Member
Yep, 2 step will trend closer to the "black body line" and 4 step can stray further from the line. So the 4 step is making less promises and will cost slightly less. What that means for us is, if you get a 4 step and it is slanted toward green, we get slightly less photosynthesis/W but if we get one slanted toward red, we get more. I would guess a redder LED would be better for flowering and a greener or bluer LED would be better for vegetative growth. It would be nice if they would simply advertise the chromacity in a simple way so we didn't have to guess but at this point we take what we can get :)
cree chart.jpg
 
R

reasonevangelist

Well-Known Member
I had the same question on my journey. Supra knows. ^^

If cost is an issue, but color accuracy isn't, go with the 4-step (and technically, it's actually possible to get a beneficial variation only possible w/ the 4-step, but now i'm "reaching"... and this particular factor should not be heavily weighted in your decision).
 
deakus

deakus

Member
captainmorgan said:
730 nm puts the plant to sleep and 660 nm wakes it up.
Click to expand...
Having read up the one thing I hopefully got right was to give as much detail as poss, which the replies have showed to be correct!
The replies are much appreciated and have no doubt saved me stress further down the line.
Someone said to me once "you can ask the silly question now,or be made to feel silly later for not asking". I've not stopped asking those silly questions since......
Just to clarify (in the simplest way):
-red 730 as supplement to wake plant in flowering.
-red 660 to put to sleep at end of flowering 12/12 daily.
I will at some point be adding a cxa3070 to my 2 cxa 3050 (2700k),should i go for 4000-5000k or something lower?
Thanks to all for the wisdom.
 
captainmorgan

captainmorgan

Well-Known Member
deakus said:
Having read up the one thing I hopefully got right was to give as much detail as poss, which the replies have showed to be correct!
The replies are much appreciated and have no doubt saved me stress further down the line.
Someone said to me once "you can ask the silly question now,or be made to feel silly later for not asking". I've not stopped asking those silly questions since......
Just to clarify (in the simplest way):
-red 730 as supplement to wake plant in flowering.
-red 660 to put to sleep at end of flowering 12/12 daily.
I will at some point be adding a cxa3070 to my 2 cxa 3050 (2700k),should i go for 4000-5000k or something lower?
Thanks to all for the wisdom.
Click to expand...
Nope you got it backwards. 10 minutes of 730 nm after lights out and if your using a white LED it should have enough 660 nm in it's spectrum to wake the plants at lights on.
 
C

churchhaze

Well-Known Member
total phytochrome (P) is Pfr + Pr

Pfr is the active form of P while Pr is the inactive form.

660nm light will make Pfr/P converge around 0.85 (the highest it will go)

730nm light will make Pfr/P converge around 0.05 (the lowest it will go with any wavelength)

In darkness, it will slowly go to 0. A pulse of 730nm will quickly shoot Pfr/P to 0.05, allowing it to reach 0 faster in darkness. This theoretically adds 2 hours to effective night length.

WARNING: When the plant is not sleeping, Pfr/P is logarithmically proportional to stretch rate. The closer to 0, the more it will stretch..... Also, shaded branches will see a lower Pfr/P because the leaves above them filtered out the majority of the red and other "good quality" colors.
 
captainmorgan

captainmorgan

Well-Known Member
churchhaze said:
total phytochrome (P) is Pfr + Pr

Pfr is the active form of P while Pr is the inactive form.

660nm light will make Pfr/P converge around 0.85 (the highest it will go)

730nm light will make Pfr/P converge around 0.05 (the lowest it will go with any wavelength)

In darkness, it will slowly go to 0. A pulse of 730nm will quickly shoot Pfr/P to 0.05, allowing it to reach 0 faster in darkness. This theoretically adds 2 hours to effective night length.

WARNING: When the plant is not sleeping, Pfr/P is logarithmically proportional to stretch rate. The closer to 0, the more it will stretch..... Also, shaded branches will see a lower Pfr/P because the leaves above them filtered out the majority of the red and other "good quality" colors.
Click to expand...
I stopped explaining phytochrome state to people just learning about it and just use the term wake and sleep to simplify it,then point them to some reading if they want to know more.
 
deakus

deakus

Member
captainmorgan said:
I stopped explaining phytochrome state to people just learning about it and just use the term wake and sleep to simplify it,then point them to some reading if they want to know more.
Click to expand...
Big Thanks to Captain &Church, I bow not only to your knowledge but also your ability to convey this to the "lay man".
Advice welcomed!
 
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