HLG ppfd concern

Hey @dbrn32 . Quick question for you and all the peeps here who are familiar with the HLG stuff…
About a month ago I bought two of the XL 260 xl rspecs to flower a 4x4. my 2 plants in the tent seem healthy and have been growing / flowering. The lights have the adjustable pot dimmers. One of the plants has been sitting at about 10 inches from the light for a couple weeks since stretch. It seemed kinda close but I haven’t had any negative effects.
So… fast forward…
Today, for a different tent, I set up a new 320 XL rspec and put it in a veg tent for my seedlings. This light DOES NOT have the adjustable pot dimmers, it has the dimmer in the driver. I turned the dimmer all the way down. Being concerned that it still might be too bright, I downloaded an iphone app to measure the ppfd. The light is sitting about 4 feet over the seedlings at 150 ppfd, seems ok. This isn’t my concern per se.
So, I measured the original tent with the 260 xls. I am getting 450 ppfd at the canopy which is only 10 inches below the lights… hmmmm??? head scratcher… If i pull my phone right to the light (10 inches closer) , it hits about 1500 ppfd. These lights can’t be working at full capacity? I always felt like my plants were too close, but there was no consequences so I didn’t question it…
What am I missing on the 260 xl’s? is there another adjustment somewhere?
footnotes-
260 xl with pot dimmer turned to 100 % is 450 ppfd at 10 inches, seems super low.
320 xl with dimmer in driver at lowest setting 150 ppfd at 48 inches, ok for seedlings, but makes me question the output of the 260’s

iPhones aren’t accurate light measuring tools. In full sunlight my app says it’s 460 umol/m2.

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Well, I guess I should have looked at the bottom of the driver before posting. There is in fact another dimmer. Problem solved. I raised the lights and turned them up to 850 ppfd at the canopy for now. The dimmer on the driver is at 100% and the pots are about 75%.

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Just downloaded the same app on my other iPhone and set them side by side. One says 460 and the other 798 in full sunlight, lol. There is no diffuser on them but even switching them around they read the same.

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I am using the Korona app. I taped a piece of plain white paper over the lens to diffuse the light. That’s what the app suggests. In the sun it hits 3000 ppfd

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Interesting. Same app.

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lol, no idea man. I’m not putting too much faith in the phone accuracy. I was able to get the light much brighter once my dumbass found the other dimmer… who knew. According to the app I doubled the light output. A step in the right direction but still no idea what the actual numbers are. I will fly by the seat of my pants and just monitor the plants until I find a happy place. I better not burn these buds now, they are pretty big and frosty. I can imagine what they would look like if I wasn’t so stupid, :joy:

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There is a table on the HLG website that will convert lumens to PPFD if using HLG lighting. Every model light will have a different spectrum, and that is what the table addresses. Phone apps aren’t capable of reading PPFD accurately as they don’t account for spectrum differences.

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thanks Fixer. I will probably end up getting a meter at some point. I’m just gonna wing it for now with slow and steady increases and see how the ladies react.

I was wondering how I could measure ppfd with 260 xl since they didn’t provide a map I was just gonna use their height but I prefer the lux meter option so much more reliable

They have a 260 map

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They don’t have one for the xl(at least posted on the store page) but thanks i can use that as a decent guide

You just have to crop it, lol

But yeah, the outer edges on the 4’ side would be higher due to the boards being spread and this is an open air test so all the edges would be higher just from the reflective walls in a tent.

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One on bottom of xlg driver is what I was thinking when I read original post. Glad you found it.

Fwiw I agree with Bobby, those apps kinda suck

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Yeah, I get that the apps suck. I was using it as a baseline for comparison and not trusting the actual numbers. I’m not into spending the money for a good meter.

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Don’t blame you, they aren’t really needed. But also shouldn’t put a lot of trust into inexpensive one either.

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