Light not strong enough, so longer light duration???

Also, even if you use the umol/s spec from your light and divide by area of coverage in m^2 - take that number and reference a DLI table with hours of operation. "40" DLI is likely a bit above what you need for ambient co2. 45 is definitely over waht you need for ambient co2. Start at 40 DLI and dial back from there. It'll save you some trial and error time dialing it in. Fwiw, the 55 they show is a good starting point for 1200-1300ppm co2. their 45 suggestion is dog shit though. Even this "40", if calculated at the diodes is an overestimate and the actual DLI will be a bit lower - photons absorbed into wall or missing the plant etc. nodes too tight, needs less. nodes too stretchy, needs more... simple as that. These values only get you in a ballpark, then you need to observe and react approriately. they are not meant to be used too literally... merely guides. The math and science is sound, but local variables do matter as far as how much your plant can handle per day vs a garden in a different location with slightly different variables.

If extremely underpowered, i'd go 24/0. If it can get 'close enough' to 35-40 DLI before that point it becomes a debate... at what point does the negative of zero or just fewer dark hours have a larger impact than the incremental DLI you add? I don't believe solid information exists on such an esoteric question. The context is only relevant to people who didn't properly size their equipment for the space. So, not a high priority to test something that can be easily avoided. "dark" cycle processes do happen in the light, too. You don't have to worry about killing the plant or anything like that. It's just not optimal to do it. --------- sorta related but unnecessary to read if you are of the TL;DR generations since 1981. I want to clear up soemthing mistated too. Stomata close at night, therefore transpiration is significantly slower at night. CO2 enters through the stomata. CO2 intake is not a major concern for the plant at night. Some businesses may run lights 24/0, but they may also blindly be wasting a ton of electicty for no reason. If they were a professional operation with the right expertise, they wouldn't have underpowered lights that require a 24/0 cycle in the first place. Whether you give X DLI over 24h or X DLI over 12-20h doesn't matter much as far as cost, either. It'll cost roughly the same wattage. You may save a fraction of a percent of watts by running already efficeint lights with a bit less wattage over longer hours, but you don't even need to do a break-even analysis to see it would not be worth it if it has any negative impact on the plants. So, if the plant benefits froma dark cycle, which it does, it's better to give it some minimum dark cycle and meet its DLI maximum over 18 hours of light operation per day. This stuff is all math and not magic. I run my vege 16/8. also creates a less drastic shift when i do switch to 12/12, because i don't grow circus clown plants (autoflowers lol, i can't resist).

Sicuramente se ha qualche ora di buio gli fa solo che bene,,da 18h a 24h non c'è molta differenza di produzione. Invece di consumo elettrico c'è molta differenza. .

18h day/6h night