Light during dark period question

So here is my deliema. I Have a few things going in my growroom while the lights are on and off. First being a humidity controller http://www.discount-hydro.com/productdisp.php?pid=572&navid=6 it is hooked up to a humidifer so that I can matain an optimal humidity in my growroom. Here is the problem with it. There are two green lights on the humidity controller and one red power light on my humidifier. I've tried covering the humidity controller lights with tape but that does not help as there are vent holes in the top and the bottom of this unit so that it can allow air into the unit to measure the reletive humidity in the air and the light leaks through the vents as well.

Is the green lights coming from my humidity controller going to give me issues??? Why in the world would a unit made for hydroponics have a bunch of lights on it? Seems silly.

I know that there is to be no light during the dark period but I don't see a way around this one other then taking the humidity controller out of the growroom which then prevents me from controlling the RH in the room.

J

Green lights don't matter...any other light brighter than moonlight is no good.
Plants are green..this is the spectrum of light that is being reflected back to our eye...which means the dark cycle is not affected by green light.

the Captain is right, green light is fine during dark times.

the chances are that it's not bright enough to give you problems. if you start getting herms etc then perhaps you should worry.

the idea that plants dont use green light is a fallacy - they use it just fine - which is lucky because sunlight and hps has lots of green.

spurr is the man to tell us about green light

if you start to get hermies, then change the genetics you're growing. If you get a good strain, it is very difficult to get it to hermie through light stress, and if you get a solid strain, then its just about impossible even when trying. So I wouldn't worry about a couple of green leds.

VerdantGreen said:

the chances are that it's not bright enough to give you problems. if you start getting herms etc then perhaps you should worry.

the idea that plants dont use green light is a fallacy - they use it just fine - which is lucky because sunlight and hps has lots of green.

spurr is the man to tell us about green light

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What are you talking about crazy man....citations,data,where's your proof. Rant rant rant....
LOL V. I assume they do indeed utilize some form of that spectrum,but it's never messed me up using green bulbs in the dark. I'd say it's safe to do,but I have never left them on longer than needed. It is an age old practice used by many.
I'm curious about how much of the green spectrum is actually used and what for.

Thanks for the replies guys. One less thing to think about in the day

GMT said:

if you start to get hermies, then change the genetics you're growing. If you get a good strain, it is very difficult to get it to hermie through light stress, and if you get a solid strain, then its just about impossible even when trying. So I wouldn't worry about a couple of green leds.

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Agreed, I've had light issues in teh past with my Northern Lights and White Widow and I've never had a hermie.

hey,

I only have a minute to post, but VG is right. The claim that plants don't use green light well is a total myth. The reason this myth came about is the use of chlorophyll A/B and one carotenoid to find the absorption spectra within PAR range (400-700 nm). That was then passed off as the absorption spectra of a live leaf (and is totally incorrect); even by biology books by some colleges!

The problem with the graph of the Chl A/B and carotenoid absorption spectra they didn't use a live, whole plant. They used a liquid extract of a single leaf inside a tube using a spectrophotometer. That is far from what happens to a leaf and whole plant while it's alive under light. There are many accessory pigments to Chl A/B. Those accessory pigments can absorb other ranges of PAR and into UV and IR; and transfer energy from that absorption for photosynthesis and other photo-biological processes.

Thus the Chl A/B absorption graphs showing little absorption of green light are not valid for how leafs use light when they are alive and under light.

Under lower irradiance white light (e.g. HID) blue light and red light provide the highest quantum efficiency (QE) and quantum yield (QY) -- absorption/usage of photons for photosynthesis. Blue and red are absorbed more than green light and they drive photosynthesis more than green light under lower irradiance white light. That said, the difference between the ranges is not a worthwhile concern, they all drive rate of photosynthesis (Pn) well. With red light providing the highest QE and QY, then blue then green. This is found with various methods, usually a photosynthesis chamber and an integrating sphere and spectroradiometer. I could explain that reasons of this but I don't' have time right now.

Under high irradiance white light it has been found green light can drive Pn better (i.e. higher QY) than red and blue! Due to greater penetration into leaf and usage by chloroplasts lower in the leaf vs. blue or red photons (they get used by upper level chloroplasts). Most people who grow with a 600w or 1000w HID fall under the high irradiance category. I can explain why this happens but I don't' have time right now.

For info on this topic looks for papers and writings by K.J.McCree, esp. for "action spectra of photosynthesis" and "quantum flux density"; along with info paper by K.Inada about "yield photon flux".

Here is a good source of older info from both authors summarized by some of the articles for the NASA convention under the "photosynthesis" heading: http://www.controlledenvironments.org/Light1994Conf/Contents.htm


To answer the OP:

At night color doesn't matter to much, while green would be the best choice, blue and red are just as OK to use; red would be the least good choice because that is the range that tells a plant when it's night and day (via. phytochrome responses). The reason moon light doesn't make plants stop flowering is it's irradiance and color (no red and far red).

The key using light a night is the irradiance and time; I found good info on this topic a little while ago. Anyway, very low irradiance can be used for longer time period. A person could use a regular flashlight at night as long as it's low power and not for long time frame (ex. <10-15 minutes).

spurr said:

The reason moon light doesn't make plants stop flowering is it's irradiance and color (no red and far red).

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I was taught the reason moonlight doesn't interrupt the flower cycle was because plants need at least .03 foot candles to break the flower cycle and a full moon is only .01 foot candles? An old guerrilla grower told me he used to go to one spot at his grow every night to smoke a ciggy and in that spot he had hermies but think that was more to do with infrared and not fc's?

Easier - pull the screws out and spray the LEDs black with paintspray.

FWIW,

K.McCree's action spectra of photosynthesis (ASP) using QY was his method to 'weight' PPFD (Photosynthetic Photon Flux Density) of a lamp using his ASP to show the lamps' ability to grow plants. Kind of like how lamp lumens are weighted more to green light for human eyes.

McCree (and others) used monochromatic lighting to find the QY of each wavelength within PAR range. He then used that data to make his QYC (Quantum Yield Curve); what we should use instead of Chl A/B absorption spectra curve once it's updated with the new data about green light. He also used QY data to calculate QFD (a single number using PPFD) to give a rating for a lamps' ability to grow plants.

What that means is the data collected by McCree and many others, incl. K.Inada, did not study light affects under white light (I.e. HID). Current research does study affects of color of light under white light; and it is those studies that show and explain green light driving Pn greater than blue and even red under "bright white light". The results are well explained form a valid scientific theory that IMO applies to cannabis. More research is needed, there is not concenceus on this yet (AFAIK); the studies are very interesting.

@ OP:

I have had little red LED's like the green ones you are referring to (on surge protectors) that I allowed to run all night, they never affect flowering but I didn't keep them right next the plants. With the light off you could see the red LED on the power strip but the light wasn't strong enough to illuminate or irradiate the flowers. So you should have no probs. with the green one. my 2 cents...

Don't they still make electrical tape?

mean mr.mustard said:

Don't they still make electrical tape?

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LOL!

mean mr.mustard said:

Don't they still make electrical tape?

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That what I use, but I think the OP meant he couldn't get to the LED's because they we're inside the controller and the light was coming out the vents.

worst case scenario - use a soldering iron to burn your way to the LED, and paint it black.

I wouldn't bother attending a green LED that doesn't shine directly on the plants, but if it bothers you why don't you just get to the LEDs and paint them black?

GMT said:

if you start to get hermies, then change the genetics you're growing. If you get a good strain, it is very difficult to get it to hermie through light stress, and if you get a solid strain, then its just about impossible even when trying. So I wouldn't worry about a couple of green leds.

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I've always been under the impression that the chemdawg line was very easy to herm from light stress...

Great info guys thanks alot. there is a light swith in my basement that also uses a bulb in my room.i wanted to put a green bulb in incase someone flips it on...

Aksala said:

I've always been under the impression that the chemdawg line was very easy to herm from light stress...

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what about snowdog?