DLI important or not?
- Thread starter KonopCh
- Start date
CobKits
Well-Known Member
yes ive seen negative effects at 24 hr with lots of light. same plants do fine at 18/6 or 12/12
i didnt used to be a believer when people say "plants need rest" but now i do.
in the cases i do 24 hr (easier to maintain if your schedule is not regular), ive turned them down to less light (300 ppfd) and they are fine
i didnt used to be a believer when people say "plants need rest" but now i do.
in the cases i do 24 hr (easier to maintain if your schedule is not regular), ive turned them down to less light (300 ppfd) and they are fine
Randomblame
Well-Known Member
The DLI says only how much light was delivered per day. For instance 150μmol/20h or 190μmol/16h in both cases you get about 11Mol/d DLI and thus identical growth rates.
KonopCh
Well-Known Member
But... is "less light" also less yield?
Randomblame
Well-Known Member
Automatics also need a certain rest phase, but only 4-6h.
That means, you can light 18-20h.
20h at 700μMol would mean 50Mol/d DLI, but no danger for bleaching.
To get to 50Mol/d DLI at 12h you need 1170μMol/s with high risk of bleaching.
In addition, less light provided for a longer period is more efficient than more light in less time.
That means, you can light 18-20h.
20h at 700μMol would mean 50Mol/d DLI, but no danger for bleaching.
To get to 50Mol/d DLI at 12h you need 1170μMol/s with high risk of bleaching.
In addition, less light provided for a longer period is more efficient than more light in less time.
Randomblame
Well-Known Member
30-35Mol/d Is the average light intensity on the northern hemisphere. You need about 800μMol/s for 12h to achieve this or 18h with 550μMol/s.
Randomblame
Well-Known Member
The higher the DLI the higher the yield, but only to a certain point. To much and you will cause stress, resulting in a loss.
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KonopCh
Well-Known Member
That I was looking for, thank you @Randomblame !!
OneHitDone
Well-Known Member
Isn't there some "wake up time" that factors in as well? It would be interesting if the longer period of lower intensity actually produced more growth
wietefras
Well-Known Member
How does that show plants need "rest"? It shows there is a limit to the amount of light they can process during a day.
Give them half the intensity for 24h and they will be fine too.
I've had plants under 24/0 for long periods and seen no ill effects at all. At low intensities. Benefit in my case was that they were in a cold room, so the temperature wouldn't stay acceptable with the light on all the time.
CobKits
Well-Known Member
sorry i could see where that would be less than clear
thats why it was in scare quotes, as its somewhat of an urban legend that they grow better under light cycles as opposed to 24 hours.
ive used 24 hours for decades but ive run into situations lately where they have been possibly exceeding DLI and stressing them, thats my only conclusion
thats why it was in scare quotes, as its somewhat of an urban legend that they grow better under light cycles as opposed to 24 hours.
ive used 24 hours for decades but ive run into situations lately where they have been possibly exceeding DLI and stressing them, thats my only conclusion
Photon Flinger
Well-Known Member
1 DLI = 277.8 PPFD per hour.
visajoe1
Well-Known Member
there is a thread around RIU somewhere testing yield differences between different flowering times as little as 10hrs. im running 11/13
MrTwist1
Well-Known Member
It all comes down to diminishing returns. Yes you will yield more with more light... up to a point.
If total yield is your priority then squeeze just as much light in there as you can without harming the plants and go at it. If efficiency is your priority then go low power, but focus on good distribution.
If total yield is your priority then squeeze just as much light in there as you can without harming the plants and go at it. If efficiency is your priority then go low power, but focus on good distribution.
MrTwist1
Well-Known Member
Yeah I believe there is a "wakeup" time to be factored in too. I like simulated sunrise for this very reason - why waste power if the plants aren't ready for 1000ppfd yet?!