LED light intensity

[wietefras]

COVERAGE AREA:

5 Square Feet at 18 inches above the canopy

PPF: 445 μmol/s

We generally aim for 800umol/s/m2 average (on the high side of things) which equates to 75umol/sqft/s

445umol/s/5=89umol/s/sqft

or 5sqft=0.465m2 and 445umol/s / 0.465m2 = 958umol/s/m2

So you would be about 19% over that, but at 18" the wall losses will probably be something like 20% too if not more. So you should be fine.

If the plants can not deal with it then one of the other "pillars" is not adequately supported. Things like nutrients, climate or CO2. Personally I have noticed if my plants were having issues with the light it later turned out they didn't have a properly grown root system. Which means they cannot take up water and nutrients in the right amounts.

 

[Humple]

Ok so back to a follow-up question to my original thoughts..

I've been doing a lot of research on light intensity. While I know and understand that a measurement of PPFD is the only way to truly know what is reaching the plants in any given place on the floor, I'm don't want to over think this so I looked for an easier, while potentially less reliable, way of getting a handle on how much light to give them.

Here are the specs on my light..

COVERAGE AREA:

5 Square Feet at 18 inches above the canopy

PPFD: 967 μmol/m2/s

POWER:

Total Wattage: 200 W

PAR Wattage: 96 W

PPF: 445 μmol/s

In my research, I've found other noobs like me relating to the wattage per square foot of growing space numbers to simplify the calculation. I know this is an outdated way to measure your light effectiveness, more appropriate for HID lighting, but if there is some way to relate that or calculate that by using the numbers for the specs of my light, that would be really helpful. It's clear to me the 50w per square foot for my space is too much light for 3500, Clu048's. I've dimmed them down to about 32w per sq. ft. to see if that helps. I think growmau5 is running even less that this.

I ask this as I don't have ttstyk or supra's or greengenes mind for this stuff, I'm not wired that way.

On another note, I think we need to remember that in our essence, we are all more alike than we are different. I didn't read through this entire thread until this morning and I've got to tell you, the bickering and vitriol is really childish. It helps no one and shows very little respect for the op. I've wanted to comment on this on other threads but as they weren't mine, it wasn't my place. However...this is a thread I started. I don't mind productive hijacks...bring it but I don't like childish bs.

I really don't care how experienced you are and how you think everyone else sucks. It just shows a level of maturity that I don't play with. So please keep it adult and productive in this thread is all I'm asking and let's help each other get better if that is, in fact, the goal. This may help someone else a few years down the road and it's better if people don't have to sift through middle school to get the answers they're looking for.

Thanks

Well said.

 

[Slinging PAR]

Ok so back to a follow-up question to my original thoughts..

I've been doing a lot of research on light intensity. While I know and understand that a measurement of PPFD is the only way to truly know what is reaching the plants in any given place on the floor, I'm don't want to over think this so I looked for an easier, while potentially less reliable, way of getting a handle on how much light to give them.

Here are the specs on my light..

COVERAGE AREA:

5 Square Feet at 18 inches above the canopy

PPFD: 967 μmol/m2/s

POWER:

Total Wattage: 200 W

PAR Wattage: 96 W

PPF: 445 μmol/s

In my research, I've found other noobs like me relating to the wattage per square foot of growing space numbers to simplify the calculation. I know this is an outdated way to measure your light effectiveness, more appropriate for HID lighting, but if there is some way to relate that or calculate that by using the numbers for the specs of my light, that would be really helpful. It's clear to me the 50w per square foot for my space is too much light for 3500, Clu048's. I've dimmed them down to about 32w per sq. ft. to see if that helps. I think growmau5 is running even less that this.

I ask this as I don't have ttstyk or supra's or greengenes mind for this stuff, I'm not wired that way.

On another note, I think we need to remember that in our essence, we are all more alike than we are different. I didn't read through this entire thread until this morning and I've got to tell you, the bickering and vitriol is really childish. It helps no one and shows very little respect for the op. I've wanted to comment on this on other threads but as they weren't mine, it wasn't my place. However...this is a thread I started. I don't mind productive hijacks...bring it but I don't like childish bs.

I really don't care how experienced you are and how you think everyone else sucks. It just shows a level of maturity that I don't play with. So please keep it adult and productive in this thread is all I'm asking and let's help each other get better if that is, in fact, the goal. This may help someone else a few years down the road and it's better if people don't have to sift through middle school to get the answers they're looking for.

Thanks

Well your first problem is believing in what the 'grow bros' on youtube think is best. Guarantee for failure. Do your own research, look at the real scientific studies done by credentialed people. Not some guy who's claim to fame is growing illegally for 12 years. Or dropped out of university with a golf scholarship having a joke for a handicap. It is those folks who turn the threads to junk with their incessant 'grow bro' ramblings over something they accidentally fell into and that others had known for years.

With that out of the way, let's get back to basics to see why some of these numbers are what people swear by.

50w/ft2 - derived from a 1kw HPS being the standard for a 5x5. 1kw over 25ft2 is 40w/ft2. Back when more was better, they tossed in an extra 10w/ft2 for good measure. If using LED then this measure is useless for growth. For business it has a direct impact on your bottom line for operational costs.

Now for figuring out LEDs scrap the power for now and strictly use the proper tools. If a new grower you probably don't have the experience to read the plants so get a PAR meter and IR thermal meter. You also need to measure ambient air temps and humidity.

Read up on how to use them. See what others report and see how they compare to your results. Eventually you will be able to correlate measured values to plant responses and won't need the meters.

The numbers you posted are fine. You got 445 ppf (that is power of the light source) to cover roughly 0.5m2 which results in just over 900 ppfd. That provides about 3.5 DLI units/hour. For a 12 hour lights on cycle, that's about 42 DLI which I consider to be very acceptable for flowering. Check the forums for other ppfd and DLI examples you might want to consider running.

When it comes to building fixtures, unfortunately citizen doesn't have the spreadsheets like bridgelux does so it is harder to plan upfront. That isn't a slight against citizen or other LED manufacturers, hopefully they will follow and provide those tools in the future.

* edit: math fail

 

[giantsfan24]

Well your first problem is believing in what the 'grow bros' on youtube think is best. Guarantee for failure. Do your own research, look at the real scientific studies done by credentialed people. Not some guy who's claim to fame is growing illegally for 12 years. Or dropped out of university with a golf scholarship having a joke for a handicap. It is those folks who turn the threads to junk with their incessant 'grow bro' ramblings over something they accidentally fell into and that others had known for years.

With that out of the way, let's get back to basics to see why some of these numbers are what people swear by.

50w/ft2 - derived from a 1kw HPS being the standard for a 5x5. 1kw over 25ft2 is 40w/ft2. Back when more was better, they tossed in an extra 10w/ft2 for good measure. If using LED then this measure is useless for growth. For business it has a direct impact on your bottom line for operational costs.

Now for figuring out LEDs scrap the power for now and strictly use the proper tools. If a new grower you probably don't have the experience to read the plants so get a PAR meter and IR thermal meter. You also need to measure ambient air temps and humidity.

Read up on how to use them. See what others report and see how they compare to your results. Eventually you will be able to correlate measured values to plant responses and won't need the meters.

The numbers you posted are fine. You got 445 ppf (that is power of the light source) to cover roughly 0.5m2 which results in just over 900 ppfd. That provides about 3.5 DLI units/hour. For a 12 hour lights on cycle, that's about 42 DLI which I consider to be very acceptable for flowering. Check the forums for other ppfd and DLI examples you might want to consider running.

When it comes to building fixtures, unfortunately citizen doesn't have the spreadsheets like bridgelux does so it is harder to plan upfront. That isn't a slight against citizen or other LED manufacturers, hopefully they will follow and provide those tools in the future.

* edit: math fail

"Well your first problem is believing in what the 'grow bros' on youtube think is best. Guarantee for failure. Do your own research, look at the real scientific studies done by credentialed people. Not some guy who's claim to fame is growing illegally for 12 years. Or dropped out of university with a golf scholarship having a joke for a handicap. It is those folks who turn the threads to junk with their incessant 'grow bro' ramblings over something they accidentally fell into and that others had known for years."

You're fucking kidding me right?? I think my post said I've been doing my research. I think I was clear about that. Did you even read my post? This section of your post is a fucking joke. Take you juvenile shit elsewhere "bro". Wtf...my god this is exactly what I was talking about. Middle school bullshit. This paragraph makes anything you said that may have been of some value irrelevant. For goodness sake! You're not schooling me or anyoe else with your approach. Just bow the fuck out.

 

[giantsfan24]

We generally aim for 800umol/s/m2 average (on the high side of things) which equates to 75umol/sqft/s

445umol/s/5=89umol/s/sqft

or 5sqft=0.465m2 and 445umol/s / 0.465m2 = 958umol/s/m2

So you would be about 19% over that, but at 18" the wall losses will probably be something like 20% too if not more. So you should be fine.

If the plants can not deal with it then one of the other "pillars" is not adequately supported. Things like nutrients, climate or CO2. Personally I have noticed if my plants were having issues with the light it later turned out they didn't have a properly grown root system. Which means they cannot take up water and nutrients in the right amounts.

Thank you for the response. My setup is just the same as it has always been it's just that the light is different and from what I've researched there is a learning curve. So far I've screwed this up lol. I'm treating it like my HID system and it's clearly not working. I think CO2 might be an issue but I'm not sure. It's like hunting and pecking right? If this then that...

Thanks again for the response.

 

[Slinging PAR]

This paragraph makes anything you said that may have been of some value irrelevant. For goodness sake! You're not schooling me or anyoe else with your approach. Just bow the fuck out.

Wow so you won't take correct information from sources you don't like because of something you 'feel' isn't right? Sounds pretty limiting. No schooling either, I could not care less what you do or don't do. I just share what I find and others can choose to do what they want.

What makes it even more funny is that it was in agreement with your post that it was in response to, containing a classic example of how terrible the internet can be on this forum.

 

[giantsfan24]

We generally aim for 800umol/s/m2 average (on the high side of things) which equates to 75umol/sqft/s

445umol/s/5=89umol/s/sqft

or 5sqft=0.465m2 and 445umol/s / 0.465m2 = 958umol/s/m2

So you would be about 19% over that, but at 18" the wall losses will probably be something like 20% too if not more. So you should be fine.

If the plants can not deal with it then one of the other "pillars" is not adequately supported. Things like nutrients, climate or CO2. Personally I have noticed if my plants were having issues with the light it later turned out they didn't have a properly grown root system. Which means they cannot take up water and nutrients in the right amounts.

So from this, I'm getting I really should have a par meter. So you have one you'd recommend?
My setup is small and although I'm tech savvy, it doesn't extend to lighting where specialized training is helpful.
Thanks in advance for any ideas.

 

[Streetsports]

So from this, I'm getting I really should have a par meter. So you have one you'd recommend?
My setup is small and although I'm tech savvy, it doesn't extend to lighting where specialized training is helpful.
Thanks in advance for any ideas.

https://www.apogeeinstruments.com/quantum/?gclid=Cj0KCQjw8MvWBRC8ARIsAOFSVBUNO2DAzbNPyeJihpACKOFrhh3lcZtfCFcI0XpEP53Cg2HgeC89iUEaAkjzEALw_wcB

 

[giantsfan24]

https://www.apogeeinstruments.com/quantum/?gclid=Cj0KCQjw8MvWBRC8ARIsAOFSVBUNO2DAzbNPyeJihpACKOFrhh3lcZtfCFcI0XpEP53Cg2HgeC89iUEaAkjzEALw_wcB

That sure seems like a nice device. I've seen this one that's a bit more budget friendly

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/162880110267

But I question whether or not it's a quality device. Anyone have one of these? Is there a calculation to find ppfd from a lux meter?

 

[nfhiggs]

Is there a calculation to find ppfd from a lux meter?

Yes, a fairly accurate conversion factor can be obtain from the SPD chart.

 

[giantsfan24]

Yes, a fairly accurate conversion factor can be obtain from the SPD chart.

SPD chart? Could you provide a link please? I just googled lux to ppfd conversion but couldn't find a conversion factor for LED in a quick search.
Thanks man!

 

[CobKits]

That sure seems like a nice device. I've seen this one that's a bit more budget friendly

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/162880110267

But I question whether or not it's a quality device. Anyone have one of these? Is there a calculation to find ppfd from a lux meter?

those actually arent awful

theyre repeatable at least

 

[CobKits]

SPD chart? Could you provide a link please? I just googled lux to ppfd conversion but couldn't find a conversion factor for LED in a quick search.
Thanks man!

SPD chart is specific to a given spectrum so there isnt just a single one for LEDs. you get it from digitizing the spectral curve

so a 3000k is differnet from a 3500k is different from a 4000k
same for 70 vs 80 vs 90 cri

even one manufacturers 3000k 80 cri might have a differnet spd than another mfr's 3000k 80cri... but they should be close and you can cheat here if needed

 

[giantsfan24]

those actually arent awful

theyre repeatable at least

By repeatable you mean they provide a consistent measurement?

 

[giantsfan24]

SPD chart is specific to a given spectrum so there isnt just a single one for LEDs. you get it from digitizing the spectral curve

so a 3000k is differnet from a 3500k is different from a 4000k
same for 70 vs 80 vs 90 cri

even one manufacturers 3000k 80 cri might have a differnet spd than another mfr's 3000k 80cri... but they should be close and you can cheat here if needed

Wow, that's helpful, thank you. Sounds like this makes any conversion a bit crap shoot?

 

[CobKits]

yes over time and from unit to unit
they probably dont have as flat of a response to the whole spectrum as the high dollar meters, so there will be a little bias, but it should be a consistent bias.

for your purposes there are a lot of other factors that will determine your success relative to "are my plants getting 800 or 830 umol". A more important use of a meter like that is "my canopy gets 1000 umol here and 500 over here, how do i fix that?"

 

[CobKits]

Wow, that's helpful, thank you. Sounds like this makes any conversion a crap shoot?

again direct par measurement is simply one data point. you can get some huge par numbers with green and blue photons but doesnt mean they are as photosynthetically active as orange and red photons.

1000 umol of sunlight vs 1000 umol of red-heavy light designed for horticulture do not behave the same way, the former has more of the less-photosynthetically-active components of the spectrum

 

[Humple]

A more important use of a meter like that is "my canopy gets 1000 umol here and 500 over here, how do i fix that?"

And with that in mind, wouldn't you say that your run-of-the-mill lux meter is sufficient? Not sure I see the value of an expensive PAR meter for your average home grower.

 

[giantsfan24]

And with that in mind, wouldn't you say that your run-of-the-mill lux meter is sufficient? Not sure I see the value of an expensive PAR meter for your average home grower.

Yes that's what I was thinking too but that said, measuring with a device that's inaccurate is the same as measuring with a wooden spoon right?? Lol

 

[CobKits]

And with that in mind, wouldn't you say that your run-of-the-mill lux meter is sufficient? Not sure I see the value of an expensive PAR meter for your average home grower.

or phone app

$140 isnt really an expensive meter imo. people spend that much all the time for ph and tds meters etc.

measuring with a device that's inaccurate is the same as measuring with a wooden spoon right?? Lol

vs not measuring? the wooden spoon can bake a nice cake in the right hands