24/0 or 20/4

[MissUniverse]

I've run 20/4 and 24/0 and I've noticed a few things. Of you run 20/4 you get a lot less nutrient problems. When I grew 24/0 my plants vegged longer but on the flip side were more prone to deformities, nitrogen issues and needed a LOT more calmag. I'd say when I lowered back to 20/4 I have had to use half the amount of nutrients than before. Also, when using things such as biofungicides and thi ng s such as azos and mykos, constant light kills the beneficial bacteria in the soil from the lack of a dark cycle. Now, I dont worry about light leaks with 20/4 and not worrying about flipping to flower is super nice... but again, the lighting can also delay flowering with 20/4 vs 24/0 in my experience. I do feel if causes the delay more in some strains over others though. Again, this is my personal opinion and I think @Waira is right on the mark about it.

 

[Frenjamin Banklin]

I just finished a Dinafem Critical plus 2.0 CBD. It was under cobs on a 17/7 light schedule in DWC. 10.5 ounces of high quality bud. Around 100 days, which is typical for my 8 galling buckets.

I think the Max DLI is going to have a huge impact on the schedule. My thoughts would be if you are running a high quality top bin cob or quantum board you can get your plants to their maximum DLI very easily and run the lights for less hours. Lower end less efficient lights might need 24/0.

It’s very easy for those running 24/0 to assume that running less would produce less. Or to say I could have done better had I increased my hours of light. I don’t think there is enough evidence with the new LED technology to make that call. 10.5 zips under 17/7 without a single deficiency for 100 days from 1 plant. And NO CO2, not bad.

It is tough for a new grower to make anecdotal assumptions stick. I think we really need those that have been growing the same strains for years to start to reduce times each grow and see if they get the same results.

I hear people comparing auto/ photo quality of smoke taste and effect. Maybe the 12/12 we flower under for photos is the reason ????? Never know, but I’m going to try less DLI. I’d like to do 18/6 for veg and 12/12 flower for an auto this fall and see what happens.

Not trying to change anyone’s opinion just wanted to offer the other end of the spectrum for comparison to 24/0.

FB

 

[Son of Hobbes]

I just finished a Dinafem Critical plus 2.0 CBD. It was under cobs on a 17/7 light schedule in DWC. 10.5 ounces of high quality bud. Around 100 days, which is typical for my 8 galling buckets.

I think the Max DLI is going to have a huge impact on the schedule. My thoughts would be if you are running a high quality top bin cob or quantum board you can get your plants to their maximum DLI very easily and run the lights for less hours. Lower end less efficient lights might need 24/0.

It’s very easy for those running 24/0 to assume that running less would produce less. Or to say I could have done better had I increased my hours of light. I don’t think there is enough evidence with the new LED technology to make that call. 10.5 zips under 17/7 without a single deficiency for 100 days from 1 plant. And NO CO2, not bad.

It is tough for a new grower to make anecdotal assumptions stick. I think we really need those that have been growing the same strains for years to start to reduce times each grow and see if they get the same results.

I hear people comparing auto/ photo quality of smoke taste and effect. Maybe the 12/12 we flower under for photos is the reason ????? Never know, but I’m going to try less DLI. I’d like to do 18/6 for veg and 12/12 flower for an auto this fall and see what happens.

Not trying to change anyone’s opinion just wanted to offer the other end of the spectrum for comparison to 24/0.

FB

I tend to agree with you on the DLI; from the research I've done on my own and talking with some of the engineers of the lighting companies here, the thought seems to be that cannabis hits that DLI range at a certain point and beyond that, more light is either not beneficial (the plant becomes light limited) or requires a change in the environment (like increased temperatures, CO2 supplementation, etc) to use that additional light/intensity. If you're running budget lights, chances are it's not going to match the screaming PPFD numbers you see say on something like a Fluence light. If the plant is not reaching it's maximum DLI in that 24 hour period, then there would be some merit there for why some see better results on 24/0 versus like 18/6 (with the same set of the lights.) The better the light (correct intensity and spectrum,) then chances are you're hitting your maximum DLI faster (and don't need the additional hours on.) I don't think there can be a "magic DLI" number but seems like there's a range that's being quantified (indicated by how intense of light we see on grow lights, etc.)

I'd say it's probably a safe statement that going from 18/6 to 24/0 doesn't turn into a 25% increase in gains (if it was that clear or evident, everyone would be doing it and it wouldn't be an argument.)

You hear this all over Facebook "cannabis is a C3 plant" when it comes to the darkness aspect. Yeah, well so about 85% of all plant life on the planet. And I'm pretty sure the sun rises and sets in MOST places in the world. Optimization is what leads to maximization, not maximization leading to maximization.

There was a grow here in Colorado (commercial grow) where the grower had a set of clones, all from the same mother. All the plants were the same height, the same age, fed the same nutrients, and under the same lights. One set of plants out of that set of clones was more light sensitive than the other for whatever reason and under the light it was at, at the same distance of the others, was getting light burned (bleached cola tips.) So even those clones in that batch showed different levels of tolerance under the same lights (in presumably a much more controlled environment compared to what we might do at home.)

 

[Frenjamin Banklin]

Agreed

I’m a hobby physicist LOL, and enjoy theories of gravitation. Strangely the lights and lighting tend to have the same issues as gravity and acceleration. Nothing is linear, and for the most part nothing we do from one hobbyist to another is constant so it is a very tough to take an anecdotal thought from one grower and say that it would be universally accepted across all grows.

I’ve grown FB GG4 several times now and it IMHO needs a lot less light that many other strains. It was my first grow under my COBs and I decided to grow it because I saw the crazy grows that bigSmo was doing with like 15w per square of light. Thinking back I can remember people thinking this was crazy. I’ve had great grows at 20w per square foot. Those were at 18/6, so if I go to 25w per can I go 17/7? Yes I just did, and I even ran 8 weeks at 16/8 and my results have been fantastic.
To be honest the plants actually have shown some light stress.

I have a small closet that I’m about to run my first ever photos and then in the fall I’m going to run 4 small Mephisto in that closet. I plan on running a indica dominant strain and vegging under 16/8 and then flower them at 12/12 and see what happens. I won’t have a previous grow of that variety but figure if I pick a 24k or Sour crack that has been run to death in the forums I’ll be able to see if the QB/cob lights allow similar yields under greatly reduced hours.

At the end of the day it will always been strain and conditions dictate what is needed. Many people like 24/0 for the heat. But if we can run find some rough linear table to get baselines for our non linear lights then maybe those guys running 24/0 can run at much less power for the 24/0. I think at the end of the day the consumption of power will be the same. I just would like it as low as possible. If it’s 25w for 16/8 and 15w for 24/0 at least we can start to formulate some hypothetical paths to take for growers to have successful harvests.

 

[MidnightSun]

I run 24/0. So talking with my daughter about why i see a benefit and others don't, (lots of the stuff went over my head) but the overview is during photosynthesis plants have light and dark reactions. Light reaction turns light into energy, and dark reaction stores Carbs. Dark reaction is a misleading name because its actually happening with the lights ON. So plants can remain perfectly healthy when exposed to light 24 hours a day. They should be larger and faster in a good 24/0 environment. - This is supported by our logs.

Now the issues, If plants are HOT they will slow down photosynthesis and this is what is probably happening with some in this thread. Solution = Lower leaf temps, adequate CO2, light, and proper food is all thats required to run 24/0.

 

[hairyman]

The place I am heading towards is a total light management system and cycle set to the maturation of the plant ,, or i will see what they have at [HASHTAG]#Poundland[/HASHTAG],, intresting thread

 

[McDee]

:smoking: It's not a linear relationship like that,... Last consensus I recall it was very conditional when it's truly worth it, mainly that last 4hours, fastly diminishing returns... Best positive example I've seen is with hydro grown monsters,....Grey Bear, a former staff had insane yields, somehow got consistently longer veg times out some of the strains he ran, and epic blow-up during stretch too! Always, 24/0,...
...I can say from what I see in Sick Bay that often as not, just because you can, doesn't mean you should,.... 24/0 under hammering light (too much, even if not showing the typical physical signs of it) seems to be causative of other issues: localized defc.'s, VPD issues, foxtailing, nanners,... not always, not consistently, but as a general trend I've noted anecdotally,... Seems strain dependent too, or maybe more accurately the Sativa : Indica balance? Point is, many can take it technically, but it's not always worth it,.. I've tried 24/0, and 20/4, 18/6,... most problems, and no significant yield improvement was noted under 24/0 vs 20/4, plus the only hermies I've had occurred under that sched'. as well,.... Often, it's a micronute issue, but seen Ca and Mg blow ups too.... problems fixed faster and better when reduced back to 20/4... It's not that the plant "needs the rest" technically, but forcing the equation, if you will, can trigger them, magnify existing ones, and be more difficult to correct sometimes,....

I always thought they like a little sleep, but no research on it. I'm about 3 weeks into my grow, would it be to late to switch to 20/4? I got a new timer and couldnt remember how to set it lol, so I just left at 24/0. This could have something to do with a few issues I've had. Always heard that once you set your light schedule you shouldn't change. Would 3 weeks be to long to change?

 

[Mizzo81]

I always thought they like a little sleep, but no research on it. I'm about 3 weeks into my grow, would it be to late to switch to 20/4? I got a new timer and couldnt remember how to set it lol, so I just left at 24/0. This could have something to do with a few issues I've had. Always heard that once you set your light schedule you shouldn't change. Would 3 weeks be to long to change?

U can switch now. Lots of folks start 24/0 first few weeks then cut back.

 

[MidnightSun]

Is the stomata open? Rub a spot of alcohol on the back of a leaf. Did it seep through the top? You will notice by color change.
Stomata Open = lights on and good photosynthesis. Closed = lights off or photosynthesis issues from environment.
So above was mentioned calcium issues on 24/0. Well Cal was probably low causing the stomata to stay closed or some other environmental issue.

Link below = Cal needed to open Stomata
https://plantstomata.wordpress.com/...alcium-in-the-opening-and-closing-of-stomata/

 

[McDee]

U can switch now. Lots of folks start 24/0 first few weeks then cut back.

Nice, thanks Mizzo! Now I got to figure out how to program my timer again lol.