Amount of light?

[Bill.de.Cat]

Sometimes you just have to stop and ask yourself....is it really worth all this effort?

 

[Delps8]

I'm using my Samsung S21 and the Photone app which I calibrated using the Viparspectra charts.
Thanks

Ah, good - you've calibrated Photone, excellent. Since that's the case, this should be a walk in the park!

A few months ago, I did a quick test of Photone vs my Apogee and Photone came out much higher than the Apogee when I tested it using a Mars SP 3000. When I looked at the raw numbers, Photone was way out of line (I was using 22# paper for a diffuser on my iPhone XS Max). Then I put the test data in Excel and, lo and behold, across all four dimmer settings, Photone was consistently reading 16% high. That was pretty impressive because, the fact that it was 16% (± about 0.1%) across the board meant that it could be calibrated. When I contacted the programmer - I'd been in touch with him early last year - and shared my findings he was pretty stoked to hear that.

My thinking - you've got a pretty good way to measure PAR, the photos of your grow setup indicate to me that you're detail-oriented, and you certainly have more growing experience than I do so, I'd go for the whole enchilada. I can't think of a reason why you shouldn't give those plants all the food (light) they can handle.

"Should I go to 75% at 24" soon?" - that's only 528 µmols so that would be "light feeding" in my book (sorry for the pun).

From an earlier posting -

"To my eye, that 100% at 12" or 14" looks pretty good. That will get you > 800 across a significant portion of the canopy and, per ppfdcharts, almost 90% will be > 700 µmols. That's a marked increase over the veg recommendation from VS and, assuming the other factors in your grow are in line, you should get a good jump in yield compared to what VS is recommending."

I'd go with 800 µmols for 18/6 when it's about before 6 hours lights out and on a day when you're going to be around the tent. Give them an hour or so then check to see how they're doing. They should be rising to meet the light. Your leaves are horizontal now, which tells them they're getting good light, but they will rise up to the light at higher light levels ("praying"). If you find any leaves are rotating on their horizontal axis, that's a method of light avoidance so that part of the plant isn't handling that amount of light. Check the plants again after a few more hours and then check them before lights out.

Starting the next morning, check them periodically during the day until you're comfortable that they're doing well.

 

[SHRED]

Ah, good - you've calibrated Photone, excellent. Since that's the case, this should be a walk in the park!

A few months ago, I did a quick test of Photone vs my Apogee and Photone came out much higher than the Apogee when I tested it using a Mars SP 3000. When I looked at the raw numbers, Photone was way out of line (I was using 22# paper for a diffuser on my iPhone XS Max). Then I put the test data in Excel and, lo and behold, across all four dimmer settings, Photone was consistently reading 16% high. That was pretty impressive because, the fact that it was 16% (± about 0.1%) across the board meant that it could be calibrated. When I contacted the programmer - I'd been in touch with him early last year - and shared my findings he was pretty stoked to hear that.

My thinking - you've got a pretty good way to measure PAR, the photos of your grow setup indicate to me that you're detail-oriented, and you certainly have more growing experience than I do so, I'd go for the whole enchilada. I can't think of a reason why you shouldn't give those plants all the food (light) they can handle.

"Should I go to 75% at 24" soon?" - that's only 528 µmols so that would be "light feeding" in my book (sorry for the pun).

From an earlier posting -

"To my eye, that 100% at 12" or 14" looks pretty good. That will get you > 800 across a significant portion of the canopy and, per ppfdcharts, almost 90% will be > 700 µmols. That's a marked increase over the veg recommendation from VS and, assuming the other factors in your grow are in line, you should get a good jump in yield compared to what VS is recommending."

I'd go with 800 µmols for 18/6 when it's about before 6 hours lights out and on a day when you're going to be around the tent. Give them an hour or so then check to see how they're doing. They should be rising to meet the light. Your leaves are horizontal now, which tells them they're getting good light, but they will rise up to the light at higher light levels ("praying"). If you find any leaves are rotating on their horizontal axis, that's a method of light avoidance so that part of the plant isn't handling that amount of light. Check the plants again after a few more hours and then check them before lights out.

Starting the next morning, check them periodically during the day until you're comfortable that they're doing well.

Thank you so much!

 

[Delps8]

Thank you so much!

You're welcome.

This really is a "listen to the plants" thing but we're just using our PAR readings to get us to a safe starting point.

 

[SHRED]

I increased the light yesterday.
Turned light to 75%
at 27" at 31 DLI

They didn't like that much light. They started dropping.

Back to 50% at 24 DLI

They perked back up.

 

[Death The Cultivator]

I increased the light yesterday.
Turned light to 75%
at 27" at 31 DLI

They didn't like that much light. They started dropping.

Back to 50% at 24 DLI

They perked back up.View attachment 1479421

Veg doesn't need a lot of light. Commercially, we ran c02 at 800ppms with 300-350umols on a 24/0 schedule for mothers and transplants through veg right before going to 12/12. So imagine without c02, we can arbitrarily subtract 25% without c02, for right around 20 DLI on the high end.

I observed stress in mother plants that received 30% more light, 400umols with c02 versus the 300umols, with leafs crinkling/drooping/loss of vigor. This all occurred within less than 24 hours of adjusting the light.

I'll keep harping on the usage of anything besides a PAR meter because they are all subpar comparatively. Phones possess various light sensors even among Apple phones that are not for measuring light in a horticultural sense, they are used to measure lux in predominantly the blue and red spectrums. The majority also max out at 32k lumens, they can't fully measure grow lights that exceed that plus the typical purpose of a smart phone light sensor is to regulate screen brightness. So when a grower relies on a phone, especially a non Apple, to adjust their lighting there will be variances. It gets worse when a lighting manufacturer may not have properly and or falsified their light testing - a PAR meter will be the best way to map out the true lighting intensity for our purposes.

Apps will use coefficients to guesstimate your lighting levels using arbitrary categories like 3/35/4/5k Kelvin readings with the assumption that the color influences the overall reading. Again, your phone uses a lux meter that won't capture certain spectra by design so the app could cause more harm than good. At that point the best you can do is rely on reading your plants and referring to your manufacturer ppfd chart.

It's like those smart watches that measure different biometrics - are they accurate? To some degree but I wouldn't trust my life or a self diagnosis based on what they find - I go to a few doctors with properly maintained/dedicated equipment to get a diagnosis. This is Photone/Korona aps vs a true PAR meter.

My general guideline is:

3-7 for seeds and clones
15-20 for veg
30-35 for late veg/stretch
35-42 for flower

 

[Delps8]

I increased the light yesterday.
Turned light to 75%
at 27" at 31 DLI

They didn't like that much light. They started dropping.

Back to 50% at 24 DLI

They perked back up.View attachment 1479421

Good that you saw that and took the right step.

The more they eat (light), the more they'll grow but too much is too much. Give them a few days, bump it again, and see how they do.

 

[Delps8]

I'll keep harping on the usage of anything besides a PAR meter because they are all subpar comparatively. Phones possess various light sensors even among Apple phones that are not for measuring light in a horticultural sense, they are used to measure lux in predominantly the blue and red spectrums. The majority also max out at 32k lumens, they can't fully measure grow lights that exceed that plus the typical purpose of a smart phone light sensor is to regulate screen brightness. So when a grower relies on a phone, especially a non Apple, to adjust their lighting there will be variances. It gets worse when a lighting manufacturer may not have properly and or falsified their light testing - a PAR meter will be the best way to map out the true lighting intensity for our purposes.

Apps will use coefficients to guesstimate your lighting levels using arbitrary categories like 3/35/4/5k Kelvin readings with the assumption that the color influences the overall reading. Again, your phone uses a lux meter that won't capture certain spectra by design so the app could cause more harm than good. At that point the best you can do is rely on reading your plants and referring to your manufacturer ppfd chart.

You get an Amen from me and you've homed in on something that the guy at Photone brought up - things are really tough on Android because there are about 50,000 Android devices out there, from dozens (hundreds) of manufacturers. Ouch.

And the 32k limit is another flashing red light - their code is designed to handle numeric values between -32,768 and 32,767. If the number falls outside that range, they should indicate that there's an error. If not, that's a sign of sloppy code.

"reading your plants" - no doubt.

 

[Death The Cultivator]

You get an Amen from me and you've homed in on something that the guy at Photone brought up - things are really tough on Android because there are about 50,000 Android devices out there, from dozens (hundreds) of manufacturers. Ouch.

And the 32k limit is another flashing red light - their code is designed to handle numeric values between -32,768 and 32,767. If the number falls outside that range, they should indicate that there's an error. If not, that's a sign of sloppy code.

"reading your plants" - no doubt.

It's why I hate the apps and advocate for a PAR meter. If we were working with low DLI, sub 25, I believe they could work well for the most part even with an iPhone - mostly.

When I was building lights, a PAR meter was instrumental after I discovered that my phone was inadequate even compared to a regular lux meter(still sucks). Above 600umols(I doubt that much in some cases) can't even be read, not particular trusting of apps at that point.

 

[SHRED]

It's why I hate the apps and advocate for a PAR meter. If we were working with low DLI, sub 25, I believe they could work well for the most part even with an iPhone - mostly.

When I was building lights, a PAR meter was instrumental after I discovered that my phone was inadequate even compared to a regular lux meter(still sucks). Above 600umols(I doubt that much in some cases) can't even be read, not particular trusting of apps at that point.

Do you have some meter recommendations?