Lighting which to use to dial in DLI

[Delps8]

Also I dont know what kind of phone you have but theres pretty good apps to get accurate ppfd readings, photone works on both android and iphone, and I believe ppfd app is android only. But theyve both been thoroughly tested next to an apogee sensor and was within 1-5% on both apps. They also both have dli calculators built in so you can get that while you're taking readings too. Just gotta select the light style closest to yours and fill out the power and hang height. Can even do PAR mapping

Photone has shown to be quite accurate. It has also proven to be highly inaccurate. Been there, done the tests.

I tested Korona with a blurple that I used in 2017 and it failed. I bought an Apogee instead. In June of 2022, I tested Photone with a Growcraft X3 and it was consistently 16% high against the Apogee which I had calibrated a few weeks prior. The killer for me was the need to wrap a strip of paper around the sensor - that's a hack that just invites error.

If you can calibrate Photone against a known good, that would do in a pinch. For me, I'd rather not use my $1000 iPhone when I can spend $35 on a Uni-T and get numbers that match the numbers from an Apogee.

Yes, they're different than the Apogee but they're just as inaccurate - the Apogee is only calibrated to 5%±. My meter tested out to +2.4% but they only certify it to 5%±.

Also, for most growers, the number doesn't matter. The key is to set your lights to a certain light level and then watch your plants to see how they handle it. If they're doing fine or if they're hurting, the grower has to adjust the light to suit what the plants can use. Sure, if plants are maxing out at 600µmols then there's a problem with the grow. But, in this case, close is good - after that, the grower has to adjust fire.

To switch from lux to µmols, 10000 lux is about 150µmols. The copy & paste from an Excel document I wrote that provides additional info. The QB boards are from HLG.

 

[gqjeff]

Also I dont know what kind of phone you have but theres pretty good apps to get accurate ppfd readings, photone works on both android and iphone, and I believe ppfd app is android only. But theyve both been thoroughly tested next to an apogee sensor and was within 1-5% on both apps. They also both have dli calculators built in so you can get that while you're taking readings too. Just gotta select the light style closest to yours and fill out the power and hang height. Can even do PAR mapping

I'm using the photonee one now on my iphone 13 with diffuser...

 

[gqjeff]

Photone has shown to be quite accurate. It has also proven to be highly inaccurate. Been there, done the tests.

I tested Korona with a blurple that I used in 2017 and it failed. I bought an Apogee instead. In June of 2022, I tested Photone with a Growcraft X3 and it was consistently 16% high against the Apogee which I had calibrated a few weeks prior. The killer for me was the need to wrap a strip of paper around the sensor - that's a hack that just invites error.

If you can calibrate Photone against a known good, that would do in a pinch. For me, I'd rather not use my $1000 iPhone when I can spend $35 on a Uni-T and get numbers that match the numbers from an Apogee.

Yes, they're different than the Apogee but they're just as inaccurate - the Apogee is only calibrated to 5%±. My meter tested out to +2.4% but they only certify it to 5%±.

Also, for most growers, the number doesn't matter. The key is to set your lights to a certain light level and then watch your plants to see how they handle it. If they're doing fine or if they're hurting, the grower has to adjust the light to suit what the plants can use. Sure, if plants are maxing out at 600µmols then there's a problem with the grow. But, in this case, close is good - after that, the grower has to adjust fire.

To switch from lux to µmols, 10000 lux is about 150µmols. The copy & paste from an Excel document I wrote that provides additional info. The QB boards are from HLG.

View attachment 1559497

I guess the positive is a lot of tests and par readngs have been done by others on the Viparspectra KS3000 with expensive meters. I can use the photone app and see what light setting gets me closet to the reading many others took. I also have access to a apogee 510 from a friend.. I just have to drive and pick it up. I have a Ca lightworks new 500 Xtreme I wanna test also. It has a much higher peak in the red light than the ks3000 so I might try that one out next grow. That too has testing done from CA lightworks and also on youtube... Its just a 3x3 and growing 4 auto's in it...

 

[Cannaficionado]

I'm using the photonee one now on my iphone 13 with diffuser...

I like it but I find that my screen needs to be completely clean and I have to remove it from my case to get a good reliable reading but thats because it has a built in screen protector. I also like to emtpy my tent and set a table in there at canopy height so I make sure Im getting a nice level reading. I like how photone has a gyroscopic leveler in it, but its too hard to keep it stable holding it.

 

[gqjeff]

I like it but I find that my screen needs to be completely clean and I have to remove it from my case to get a good reliable reading but thats because it has a built in screen protector. I also like to emtpy my tent and set a table in there at canopy height so I make sure Im getting a nice level reading. I like how photone has a gyroscopic leveler in it, but its too hard to keep it stable holding it.

I was reading some posts about it and many said the best results they saw were using the natural sunlight selection?

 

[Cannaficionado]

I was reading some posts about it and many said the best results they saw were using the natural sunlight selection?

Probably because its the broadest spectrum. But idk what the capability of light sensors are on phones as far as overall spectrum detection though. I think that plays a pretty big part in the calculations on the app.

 

[TempleTrees]

Having said that, cannabis will return a good crop at 43mols. The light compensation point, below which plants cannot produce enough glucose to sustain life, is 64µmols for cannabis so growers could drop their lights to low seedling levels — think of all the money they'd save on electricity! ;-)

Do you happen to have the source for saturation @64DLI? Not calling you out, Id just love to read the study

 

[Delps8]

Do you happen to have the source for saturation @64DLI? Not calling you out, Id just love to read the study

The figure was cited for the light compensation point being 64 µmols. Cannabis will thrive with a lot of light. I grow autos at 20/4 and have run them at DLI's in the 60's and 70's.

The only place I've seen the light compensation point stated is here and I see now that it's 63µmols rather than 64µmols.

The graphic below is from the Chandra paper on cannabis at varying temperatures and DLI (using CO2). If you look at the intercept of all of the curves, they break the X axis at about that value. "about that value" is imprecise, granted, but it does lend credibility being that close to 64.

 

[TempleTrees]

I’m familiar with the study. I re-read it just to make sure, and there is nowhere in the study that I can find that describes their light interval used. I understand that 1500 ppfd x 12h = ~64 DLI, and I think this is a reasonable assumption (12H). If anyone else can find what light interval was used in the study, please let me know. I may have glanced over it, but I believe it is not described in the study.

Nevertheless, I highly doubt that the study did use an 18/6 or higher light interval. Even at 18H of light @ 1500ppfd, that’s a DLI of 97. That doesn’t seem reasonably possible. Attached photo just for perspective and fun.

Additionally, for the ease-of-use for future readers ~65 DLI is reached under:

1500 PPFD @ 12/12
1000 PPFD @ 18/6
900 PPFD @ 20/4
820 PPFD @ 22/2
750 PPFD @ 24/0

 

[Talonxracer]

I picked up the Photobio from Phantom and its measurements are within a BPH of the far more expensive Apogee. And it is far more reliable than iPhone based apps.