I’m only doing 24/0 cause my timer is a POS!
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24 for seed starting up until true leaves then 18/6 for actual veg for me
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Get a sonoff on it unless it’s HPS, MH or CMH 
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Agree with this if you pay enough attention it’s perfectly visible daily
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Do you have a link to put one of these together? Can I also attach humidity and temp gauge to this to run fans also?
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Here’s one I made earlier 
More than happy to help you if you get stuck too. There’s a few US sides that know your circuits better than me but I got the jist
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18/6… Plants need to rejuvenate, just like us human beings…
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I’ve run 24 on but only when rooting clones or cracking seeds then 18 /6 for veg
Now I’ve run autos at 24 on
Papas
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went with 18/6 but have always used 14/10 to veg
and 10/14 to flower
peace
Dequilo
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In one tent, cuts to clones/seed starting, upper section, once up potter down to lower section, is on 24/7.
In another tent, uppt to flower container size, is set up to start their ride into the flower tent, is on 18/6.
Flower tent is usually on 11/13.
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Nowadays I mostly run at 20/4. I use 24/0 for clones and seedlings.
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18/6 for flower cycle as well
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went with 18/6 but am going to try doing longer days with slightly less intense light. Like 20/4 or 22/2.
I recently watched an interesting lecture on the Apogee Instruments Inc. Youtube channel. The video was called photosynthetic efficiency and supplemental greenhouse lighting. The speaker was Marc van Iersel. The conclusions that they were getting to from that video was that as the plant receives more intense light the quantum efficiency goes down and that longer photoperiods resulted in greater light interception and higher quantum yield of photosystem 2. I will admit a lot of this went over my head but It was interesting to see an increase in efficiency with lower ppfd over a longer period vs higher intensity for a shorter period with the same DLI.
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(Forgive me if this is terribly off-topic or circuitous. My ADD is kinda in overdrive today.)
(Not sure if this link is gunna work so if not:
doi:10.1111/j.1556-4029.2011.02024.x
The Effect of Electrical Lighting Power and Irradiance on Indoor-Grown Cannabis Potency and Yield )
These dudes are averaging a little over a p per square meter with plain ol’ philips HPS across three different light intensities. 3 week veg, 8 flower, ambient co2 only. They report intensities at W/m2 but after checking some references for the bulbs in question:
600w/m2 of philips Son-T = ~1000umol
so 270w/m2 should be around 500umol
https://www.waveformlighting.com/horticulture/daily-light-integral-dli-calculator
Plus a DLI / PPFD calculator says they’re between 20-45DLI. Even at the lower light intensity they’d probably be better off adding a lil co2 rather than more light. ~45DLI is 500umol@24/0 and 700umol@18/6. Granted we’re talking veg schedules, not flower, it applies to autoflowers.
(Addendum: Based on this photosynthetic efficiency chart 1200umol at ambient co2 will be, more or less, equivalent to 400umol at 1400ppm co2. That seems too simplistic for reality, so I would love if someone would prove me wrong.)
(These two graphs are part of this article.)
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18 on and 6 off…
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Both, fascinating and excellent posts @neogitus, @Worcestershire_Farms .
Need the carbon for carbon fixation, most of the mass of the plant is from carbon. Otherwise, plant protective mechanisms turn on if it receives more light than it can utilize and fix at any one time. And, then there is the Pr and Pfr conversion to consider.
If we are talking ADD, there are some measurement tools available to measure the PS efficiency, as well; and you can see the efficiency change as the intensity increases. This thing for instance:
Coincidentally, I just finished wiring up a DIY CO2 controller this morning…
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Very interresting but i don’t get the last graph ratios : 5 (clone) : 6 (veg) : 14 (flo), i can’t believe it’s weeks. I miss something.
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Yeah, that’s the intensity for each of the weeks from the people in that last article. It’s a weird chart tho, and the weeks are listed at the top but the words at the bottom look like they’re every 5 days or so, instead of weekly
2 weeks to clone, 3 more weeks for veg, and then 9 weeks of flower
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Make more sense, thank you.
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We Always go 15/9…
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