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Vanilla Gorilla

Auto Flower Lighting 24 or 18 Hrs?

What is the general consensus on how much light an auto flower should get to maximize yield, is it 24 or 18hrs?

Should the plant be given a few hours darkness, although not entirely necessary, and have chance to recuperate?

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I always run my autos 24 hours.But as I have never tried 18,or 20 hours,I could'nt say whether yield is increased or not.

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I run 24hrs

I tried 20/4 but temps dropped considerably and humidity shit up to the 80'

Now I find I can maintain a stable environment better on 24hr schedule

 

Think it is very much either or, depending what suits yourself

I think its a question that can go on forever as people using different light times are still getting great results regardless

 

 

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I am a 24 Hour man as per the guru Blackpool Bouncer.

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I used to Run 24 As mentioned above for keeping environmental's consistent but.... if your using one Light and its on all the time probably not good for the equipment.

(even if the plants dont mind it, your lights might not.

20 for me. sometimes 22.

In regards to plants needing sleep ...... I'm drawn between making the most that they are autos and flowering them for as long as i can and resting the equipment and potentially, plants needing sleep.

its also going to depend on how powerful your lights are to some degree given plants can reach a saturation point of light.

it's hard to research because most things are done from a photoperiod perspective. I'm unsure myself where the detail lays i've seen many good grows 24 as i have with 18 or 20 

so for me 20/4 -22-2

if you give them a break at 12-4 oclock then you need less heating time of year depending to maintain good lights out temps.

Your humidity shouldn't shoot up during lights off .... keep your extraction on full power on 24 regardless of your light hours  And if its not enough consider getting a dehumidifier or re looking at your extraction setup.

 

 

Specific to CMH bulbs

"Calling maxibright was more or less useless they don't know the answer to the question. I looked at the philips website on the safety and tech PDFs on their website, and basically like any lamp the longer you run it the quicker the spectral output and PPF drops off. The question still begs, can you run a 315w on 24/7? The answer is NO. CMH lamps operate at extremely high temps, leaving them turned on 24/7 for months on end can cause the lamp to become too hot and rupture which is pretty dangerous as there is a vacuum inside the lamp which causes an implosion - lots of flying shards of glass.

 

In terms of actual spectral output and stuff, of course leaving them on 24/7 causes drop off but then so does running them on any light cycle 24/7 just gets you there quicker, but 24/7 doesn't make any sense as plants need a dark cycle and your lamp needs to cool down."

 

The above is  quote from Golden Syrup in topic called 315 cmh failing

 

 

 

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Fan of 20/4 here. 

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I'm on 20/4, i thinks its appropriate to give the lights a break and the plants a rest, gives a window to do any foliar spraying required in darkness.

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I've run both 20/4 and 24/0 before, I prefer 24/0 to maintain a steady environment in winter, but also have concerns about leaving a lamp on constantly for about three months.

Next time I do autos it'll be 20/4, with a tube heater for lights off if it's cold. :yep:

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