How close lighting in veg stage?

I have a 2’ x 2’ x4’ tent using a Samsung Maxsisun MF1000 grow light (200w output). The manual suggests 100% brightness that’s 18"-20" above canopy (18h on - 6h off). Should the light be closer than that to the canopy??

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Download the photone app for your phone.

I follow this pretty close. App will give you numbers.

Clones, seedlings. This is for seedlings. Clones can actually start in veg… since they already are. So the graph is but isn’t wrong. It isn’t wrong if you change the word clone to seed… since clones with that little light will take two weeks or more to root. Which a lot of people think it takes that long… Wonder why… lol


Budz gave you a great answer. I also use Photone but for adjustments I just use LUX and the algorithm for Full Spectrum. A repeatable number that you can correlate to what your plants show you is what you could use the most. I used to use “watts” from the wall but that’s meaningless because different lights draw different current from the wall to produce the same output so watts from a usage meter doesn’t give you the best info, but again it’s a repeatable number you can use to correlate between visual effect on the plant and the “watts” you see coming from the wall.

Also consider that there are probably no phones that actually can measure PAR, this app is calculating all that for you as are the algorithms you pay for in the app. They’re probably close enough.

In short, if you have no other tool and want something better than a watt from the wall meter or using the mfg recommendations get a free phone app and use that as your guide like Budz suggested. It should provide you with a repeatable number and in this case, you should get a close proximation of the DLI or LUX you’d prefer to see for whatever stage of life your plant is in. Depending on the light you use you may need to purchase the formula for it as I did for full spectrum.

On last thing. You can get the majority of lights to produce flowers. Quality of spectrum and intensity are what bring the bigger numbers you probably seek. Setting your light at 18 inches produces what size spread over your plants? I know with mine I keep it 24 inches or so from the canopy to get the best coverage at the sides and since I have room to spare I can bring up the intensity a bit to equalize what the canopy sees. And since I’m using Photone for measurement I seem to be achieving a DLI of 45 and a LUX of 45K at the canopy and I’m only using 70% of the light. That doesn’t make so much sense when you see people talking “watts” of consumption required to get the big numbers.

What I haven’t investigated yet is the correlation between distance and intensity. As in do I get the same penetration value at 24 inches at 50% that I would get at 48 inches at 100%. Simple math would say it’d be the same but physics may have something to do with penetration vs how hard the LED is driven coupled with distance, LED lens etc.

Get a free phone app Chauncey and check the values in the middle, front back and sides of your tent at the distances you currently have your light and try to shoot for the values Budz posted while getting good coverage near the sides of the tent.

You’ll be good to go and with enough juice, achieving the values you seek with the light you currently have at the best distance from the plant.

One other thing, once you’re at max intensity in veg you can’t go any higher which typically a lot of us will up the intensity during flower. I do it just because the DLI goes down when you drop to 12 from 18 hours.

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That’s a lot of information right there. But as a beta tester for Photone. I can guarantee you that if you take a minimum 11 measurements across your canopy and average that number. That’s your dli… it’s doing all the math except the averaging for you. Dli numbers themselves are controversial. But… DLI is quickly becoming the community standard. Since it works for everything…

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Hey Budz, as a beta tester did you get any inside info on how they convert to get PAR? There are a few websites out there that will do the calculation for you, I get slightly different values when I plug in the LUX value for 12 hours to calculate compared to the phone. I’m sure the formulas are the same it’s whether they need to adjust for camera brands etc.

That’s why you check your calibration against another meter or go to the website that tells you bright the sun is at your location on that day with a clear sky… easy to calibrate. It keeps up with my lux meter well up to 200k. That’s when my lux meter caps out. Lol. Not photone. Well not with my phone anyway. (Don’t currently have light cranked up. But you can see. Measuring off of the hydrometer that hangs from light…

137,200 vs 137,000… Less than .2% discrepancy.
The beta was more accurate. Because it went to single digit lux all the way up. Not sure why that was removed for final release. Probably bogged down lesser phones. I forget how many processors mine has… 8 or 16.

Checked. 16. Lol. Two octa cores.

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