Temp during dark periods?

it's not about personal preference... either the light is weak and needs extra hours per day to match stronger lights or it does not.... giving more light than it can handle is just throwing electricity away for an e-peen that does nothing. DLI is an apples to apples metric measuing how many photons of light provided to the plant per day... google for more information on that. This will only be for autoflowers... any switch to photos needs to redo math for 12/12 cycle, then work backward from there as far as how much area you can cover and how much you'll need to dim in vege -- hint, proporitonal to hours of use difference. E.G. If going from 20h to 12 h, it needs 166% more light when you reduce hours per day. 18 -> 12 is 150% ..you can see this is proportional and assumes you maintain the same distance from canopy, because that should be based on optimal coverage of a preordained size of area anyway. 250w custom... lm301-based LED? Probably somwhere between 625umol/s and 725umol/s produced depending on efficacy. if around 0.25w/diode you can probably go as low as 22-25w per sq ft of coverage on an 18/6 schedule. Geometry should dictate height from canopy to cover a specific area in an optimal way. The harder you run those diodes, the less efficient they are, therefor will need more watts per sq ft. The bin of your diode causes a 10-15% swing in efficacy too. top bin and runing at 0.25w per diode and you can go as low as 22w per sq ft. 250 / 22 = max coverage while maintaining max DLI in 18/6 is 11.36 sq ft. Less efficient and you need to assume it covers less space accordingly. If you have more accurate info on umol/s produced by your diy light, you can very easily calculate the DLI you provide... if it exceeds 40 by any significant amount you will need to dim or raise the light in order to avoid burning plant.. .you coudl also run it fewer hours per day and save watts too... all 3 options have various pros/cons. Now, that's all relative to "max DLi' under ambient co2 conditions... = 35-40 DLI. You can go as low as 22 DLI and still produce somethign that resembles good buds. At some point it just gets larfy. Maybe 90% of max provides best yield per sq ft and time invest? nobody can say for sure without an immense amount of resesarch with very large sample sizes of diverse strains etc etc... so, no point in assuming things, but somewhere near top range is almost assuredly better than lower range, obviously... light powers growth... diminishing returns are seed when you boost co2 to 1300-1500ppm and try to give 60-65 DLI... as you add more you get less in return up in those ranges compared to ranges associated with ambient CO2 where you should be pretty confident that the relative max is your best bang for the buck. understand this stuff and you can avoid stunting your plants... you can be confident you are giving ruoghly as much as you can... only a smallamount of fine-tuning from observing plant and reacting will be necessary to dial it in further.. these are good starting points that will require very little effort to dial it in. figure out what your light provides... convert to PPFD, reference DLI table to choose a smart light schedule relative to intensity of light and not just picking "20" because it's bigger.. .lol.