Are we using too much light?

[Mayne]

It will go to 440 watts when turned up all the way.

thats awesome man, i think i read about your rig if i remember correctly, cant remember, lol..

 

[Mars Hydro]

we know that Sara, but not everyone can buy a PAR meter, that just converts LUX anyways, its a big LED community scam. I have done tests to confirm this also, so its not just me talking crap, PAR is great for the producers of the light for a Selling Point, but in little home grows, Lux meters work just fine, staying with the notion that LED growers burn their plants because they give them to much light, and thats a fact.

Intensity is intensity regardless of light, and Both the $153 PAR meter and the $30 Lux meter is just the same, The Lux degrades with distance, as does the PAR meter, at the same rate.

Yes, at that point your right. At the old days when we don't have par meters, we also only test with lumen, but usually good chips are with higher lumens and par as well. So it can be used for reference.

 

[Vegan4life]

I Have a cheapo Dr Meter, Lux meter that I use, The guide below is what I have been following, It is from GWE


Quick Guide – Lux Levels for Optimal Cannabis Growth

Life Stage	Maximum	Good	Minimum
Vegetative	70,000 lux	40,000 lux	15,000 lux
Flowering	85,000 lux	60,000 lux	35,000 lux

< 15,000 lux – sparse or “stretchy” growth – plant isn’t getting enough light
15,000 – 50,000 lux – a good amount of light for healthy vegetative growth
45,000 – 70,000 lux – the optimal amount of light for cannabis plants in the flowering (budding) stage. If grow lights produce a lot of UV light (such as LEC), stay on the lower side of this range
70,000 – 85,000 lux – a lot of light, some strains thrive at this light level, but some plants (especially auto-flowering and Indica strains) lose their top leaves early under this light intensity. At these levels, lights need to be kept further away for healthy growth
> 85,000 lux – at this light intensity, you’ve hit the plant’s “saturation point” which means your plant can’t use all the light (most strains will experience light bleaching or other major signs of stress at this level!)

 

[Jay T Trichomes]

This is only my 2nd grow, but everything I’ve read for the last few years says ppdf is the best reading to take for plants? Am I wrong for thinking this. ? Here is a pic of the meter I use to measure Ppdf. This pic is from weeks ago and it shows ppdf around 900. That was my sweet spot for early on in flower. They are weeks past that now and I have my lights close enough to get about 1050 ppdf. And they seem great. I’ve also heard that anything above 1000pdf is pretty much useless unless you have a sealed room and c02 levels high? What’s everyone’s thoughts on that.? I have never even measured lumens in any of my tents. Should I be???

 

[TorturedSoul]

This pic is from weeks ago and it shows ppdf around 900. That was my sweet spot for early on in flower. They are weeks past that now and I have my lights close enough to get about 1050 ppdf.

. It's PPFD, by the way, not PPDF. We understand what you mean, but if you ever feel the need to do a web-search for information, getting the letters' order correct might save you some time.

Here is a pic of the meter I use

Nice meter, Apogee makes good ones. Be sure to check the manufacturer's website to see if a firmware update is available, as they do occasionally release updated code. For example, I was reading some related information at a reefer (salt-water coral enthusiast) website one day and saw where someone had tested several popular PAR meters against a very expensive meter that was known to be accurate and calibrated, something that some of the companies use for testing/R&D I think. Anyway, the person discovered an issue with a couple of meters, one of which was an Apogee. He contacted the manufacturers with his findings and was contacted back by someone at Apogee a week or so later; the person stated that they had just updated the firmware for that particular model and invited him to test it (problem was fixed). I consider that a good indicator that it's a decent company... Far better than when many people report an issue to a company and they only end up quietly releasing a fix a year later (if at all), IMHO.

Yeah, you're on the cusp of rapidly diminishing returns, I'd guess. Adding more light-energy to what you're already supplying them probably wouldn't give you much in the way of benefits unless you were also adding supplemental CO₂ (and providing the warmer temperature to facilitate things).

Good job! Do you get a lot of requests to borrow your meter? Can I be your neighbor, lol?

 

[Jay T Trichomes]

Thanks for the info tortured! Yes I take my meter to quite a few diffrent places. And phone must have autocorrected ppfd to ppdf. Only my second grow but been around some cannabis vets for quite some time.

 

[Mayne]

28,000 lux, about 430 PAR entire life, day 74 from seed, 12/12 from seed.

 

[Mayne]

20,000 lux, about 305 PAR 12/12 from seed, day 74, Over water stunted at beginning, was solo cup experiment to see if i could water everyday, then decided to transplant and it slowed it down, so about 2.5 weeks behind, same genetics as last post pic above.

 

[Mayne]

less then 15,000 lux, about 230 PAR, Cherry Wine CBD- 24 days from seed, 12/12 from seed, but 3 days ago, topped again and 18/6 now. Might scrog, might throw in the bin,lol.. undecided, its a 10 week flower strain, not sure i want to take up my entire area for 10+3 weeks more, when i can put in my FireOG cross and be done start to finish in 65 days, hummmmm, but the cherry wine grow fast as heck. She sexed in like 16 days from seed, my FireOG cross sexes in 21-24 days from seed. tuff decision.

 

[Grassmaster]

This guy says 800 foot candles is enough to grow decent cannabis with. Not great. But decent.

I'm measuring 1500 foot candles at the top of my smallest plant. And over 4,300 foot candles at the top of my tallest plant 1' from the lights. I'm only using 140 watts with my 4 cob system. According to this I have plenty of light and don't have to turn it up higher through the whole grow. LUX is roughly the foot candle reading multiplied by 10.

 

[Boneswalsh]

ok, i watched vid, and yeap, he hit it on the head.

seedlings need 5,000-10,000 lux 1-4 week veg, 20,000 Mid flower to finish, 35,000 lux is just great. The thing with the sun is, the plant matter is cooled, and doenst have a blanket of heat on it, like the LED would be, so the plant has to work double time to cool itself, then u get deficiencies, because the plant is using up Mag and potassium to keep herself cool,

If you drop temperature can you drop lux?
I moved my plants in from outside cause of temperatures and my lights only can put out 30k lux?

 

[Delps8]

If you drop temperature can you drop lux?
I moved my plants in from outside cause of temperatures and my lights only can put out 30k lux?

Why do you want to reduce light levels? Research indicates that there is a linear relationship between DLI, plant yield, crop yield, and crop quality up to a PPFD of 1500µmols.

Many growers have read the research about photosynthesis starting to roll off at 500µmols, myself included, but there are at least two research papers, one by Bugbee, that both demonstrate the impact of PPFD on plant and crop yield and quality.

30 lux is a PPFD of about 510µmols using a conversion factor of 0.017. My understanding is that's a commonly used factor to convert lux to PPFD.

As stated above, a lux meter and a PAR meter read different parts of the PAR spectrum but the 0.017 conversion factor can be used very successfully and, arguably, instead of a PAR meter. I say that having spent about $500 for an Apogee MQ-500.

At 510µmols, your DLI will be 33mols at 18/6. If you're growing autos, go to at least 20/4 since that will get you about 37 mols.

The light levels that people are reporting here are staggeringly low to me. In one of his videos, Dr. Bugbee says that almost all of the companies with whom he consults are "leaving money on the table" by not giving their plants enough light.

Characteristics of plants that aren't getting "high light", which Bugbee says starts at 45mols, are that they are very tall, have a large internodal space, and tend to have airy buds. Many of the plants in this thread have those characteristics.

 

[Buds Buddy]

I have a LUX Meter. Rarely even use it anymore. I just go by the plants leaves these days. If they are praying.... they are good. If they are turning down or cupping or twisting sideways the light is too bright. I personally feel this is the best way to determine how much light the plant needs. I do increase my light strength little by little through the grow. But I'm at 100% by the end of flower which puts me at about 65,000 lux. Not all strains will need the same amount of light so I find that letting the leaves decide does the trick better than a lux meter.

 

[Hapshoot]

Look, when you have 1 light, knowing your lux is important, not because of spectrum or anything, but knowing your intensity that you have. Thats allllll it does, measure intensity, IN YOUR GROW AREA.

If you have a 300 real watt light, you veg with HALF of what the TOTAL intensity to the height you can get nearest your LED before burning. SO, THAT is your ceiling, and You take HALF that LUX, and that is your baseline for Veg, because when you Flower, you want to double your veg watts.

So, knowing your total lux possible, You know what you should be giving your plant from seedling to finish.

You dont give a seedling 1000 PAR, You dont give a week 4 veg 1000 PAR, UNLESS, your flower is 2000 PAR,

My plant is flowering nicely at 30,000 lux, and NEVER gets more then that,

BUCKET SIZE Matters, because a 1 gallon will only grow so many roots, and more roots, OR BIOMASS, In a 3 Gallon, will grow MORE BIOMASS, and a 5 gallon will grow more then the 3, should anyways.

a Stalk of 1/4 inch thickness, cant take the amount of light that a 1/2 inch thickness stalk, because its LESS BIOMASS, and needs less light then the larger stalk.

Stem thickness is relative to lux, AND nute PPMs, AND BUCKET SIZE, AND WATTS,

a LUX meter gets you dialed in, because you can give your plant to much light, and a lux meter shows Intensity.

I have a very precise plan im following with certain things right now, and LUX or light intensity is the main narrative for it.

I havent even watched this dudes video yet, because he is wrong on alot of things,lol..

Bottom line is, you dont give your plant the same flower intensity that you would give it 2 weeks in veg.

ok, now i will watch the vid,LOL>.

oh yes, i totally agree with you. My plants LOVE getting 30,000 lux during flower. So we break that down backwards in time....dialing down the lux all the way back to when my plants were mere seedlings pushing the helmet shell off of their heads, freshly popping out of my grow medium....

Before i had my light at 30,000 lux, and about 20inches above the canopy.....i had it set to about 20,000 lux for a little while, then ramped it up to 25,000 lux for a few days, just by lowering it down from about 26inches above the canopy, to around 22 or 23inches above the canopy. I had been growing my plants in veg for a while, with the light giving them 18,000-20,000lux from a little over 2feet above the canopy.

Before that....when i first started to bend them over or train them in any way....i had my light about 30inches above them, giving them around 15,000lux....and then just lowered my light some to give them about 18,000lux when i handled them for the first time, lol...bending or cropping or anything.

And finally, before all of that....i had my light set to a little less than 3 feet above the soil, and giving them about 5,500 lux to 6,000lux until their seed shell helmets came off, and their two main baby leaves spread out...then i waited for a couple of days and set it to about 7,000lux and cruised for a couple of days letting them grow up in lux intensity as their tops got closer to the light, little by little.....until i saw that they were ok and doing good, having grown up into receiving about 8,000lux and liking it, then i lowered the light some and started getting them up to 10,000lux, growing good...looking like i might be able to crop or stress or bend soon, so might as well see if they are ready for 15,000lux maybe 18,000lux......and here we go chopping on them, bending them, etc...lol.

 

[bluter]

hi @Hapshoot welcome to the show

don't forget head on over to the intro section and tell us a little about yourself.

Introduce Yourself

Your opportunity to tell the 420 community a little about yourself and your interest in cannabis with a brief introduction

www.420magazine.com

 

[Delps8]

oh yes, i totally agree with you. My plants LOVE getting 30,000 lux during flower. So we break that down backwards in time....dialing down the lux all the way back to when my plants were mere seedlings pushing the helmet shell off of their heads, freshly popping out of my grow medium....

Before i had my light at 30,000 lux, and about 20inches above the canopy.....i had it set to about 20,000 lux for a little while, then ramped it up to 25,000 lux for a few days, just by lowering it down from about 26inches above the canopy, to around 22 or 23inches above the canopy. I had been growing my plants in veg for a while, with the light giving them 18,000-20,000lux from a little over 2feet above the canopy.

Before that....when i first started to bend them over or train them in any way....i had my light about 30inches above them, giving them around 15,000lux....and then just lowered my light some to give them about 18,000lux when i handled them for the first time, lol...bending or cropping or anything.

And finally, before all of that....i had my light set to a little less than 3 feet above the soil, and giving them about 5,500 lux to 6,000lux until their seed shell helmets came off, and their two main baby leaves spread out...then i waited for a couple of days and set it to about 7,000lux and cruised for a couple of days letting them grow up in lux intensity as their tops got closer to the light, little by little.....until i saw that they were ok and doing good, having grown up into receiving about 8,000lux and liking it, then i lowered the light some and started getting them up to 10,000lux, growing good...looking like i might be able to crop or stress or bend soon, so might as well see if they are ready for 15,000lux maybe 18,000lux......and here we go chopping on them, bending them, etc...lol.

Good to see people using a lux meter!

Would you like to increase your crop yield by more than 50%? If so, read on.

When I started growing, I didn't get a lux meter, unfortunately. I tried to use Photone and, after testing it and trading email with the programmer about it, I bought an Apogee*.

The Apogee is a great product but it's $$ so I recommend that growers use a light meter (the Uni-T Bluetooth) and then get their grow to the light saturation point as soon as possible.

One issue with using a light meter is that light meters measure a different part of the spectrum than what plants use. Light meter display results in lux but agriculture measures light as µmol ("micromols").

How to convert from lux to µmols?

"There's an app for that"…called a calculator.

Or you can use a table or do the rough math in your head.

Or you can just run with it that your grow should be at 60,000 lux and you won't have to read the rest of this message.



But, if you're interested in how things work under the hood canopy…

In the PDF on lux that I've attached, the table covers a variety of lights and gives the converted PPFD values vs the lux readings. A standard white LED has a conversion factor of 0.015 vs a really blue light (0.013) vs a dedicated flower light (0.016). It's best to use a factor that matches your light or as close as you can get but close is good enough in this case.

Here's my pitch - your results were great at 30k and that works out to about 450µmols. That's about 50% of the light saturation point for cannabis. You were happy with the results at 30k lux and that's great. If you like how things are turning out, don't touch a thing.

So where's the 50% increase figure coming from?

Read on.

Research tells us that crop yield and quality increase in an almost linear manner as light levels increase, up to the light saturation point (the LSP is 800-1000µmols, depending on the strain). I've attached a paper that discusses this**.

I've created the table below, based on the formula in the paper.

The table was created using the formula for the yield curve and, in the PDF, I started the table at 600µmols because that's the minimum recommended amount for flowering cannabis.

What the table above indicates is that, in the plants that were grown for research, if the increase in yield between crops given 600µmols of light and 900µmols of light was 23.7%. Yup, by turning the lights from 600 to 900µmols, the crop yield would increase by almost 25%.

In the case of the grow that was at 450µmols vs that same grow at 900µmols, the increase in yield was 57±%.

You've taken the step of getting a light meter (I recommend the Uni-T Bluetooth meter or, if you want a PAR meter, I'd go with either an Apogee, a Li-Cor, or the Spot On). The next step is increase your light levels to hit a limit in the range of 800-1000µmols. Assuming that light was your limiting factor, your yield should increase significantly. Per the research, I would expect it to be somewhat more than 50%.


*I've been a software engineer for 30+ years, including three for Apple, so I have some insight into the software and hardware problems that he's dealing with. For a variety of reasons, I don't use Photone and I recommend it under only certain circumstances. I strongly recommend growers use a lux meter and get their grows to the light saturation point as quickly as possible.

**The Chandra paper, which shows that the curve starts to roll off at 500µmols is measuring net photosynthesis. The paper I've cited and attached deal with crop yield and crop quality.

 

[Hafta]

Good to see people using a lux meter!

Would you like to increase your crop yield by more than 50%? If so, read on.

When I started growing, I didn't get a lux meter, unfortunately. I tried to use Photone and, after testing it and trading email with the programmer about it, I bought an Apogee*.

The Apogee is a great product but it's $$ so I recommend that growers use a light meter (the Uni-T Bluetooth) and then get their grow to the light saturation point as soon as possible.

One issue with using a light meter is that light meters measure a different part of the spectrum than what plants use. Light meter display results in lux but agriculture measures light as µmol ("micromols").

How to convert from lux to µmols?

"There's an app for that"…called a calculator.

Or you can use a table or do the rough math in your head.

Or you can just run with it that your grow should be at 60,000 lux and you won't have to read the rest of this message.



But, if you're interested in how things work under the hood canopy…

In the PDF on lux that I've attached, the table covers a variety of lights and gives the converted PPFD values vs the lux readings. A standard white LED has a conversion factor of 0.015 vs a really blue light (0.013) vs a dedicated flower light (0.016). It's best to use a factor that matches your light or as close as you can get but close is good enough in this case.

Here's my pitch - your results were great at 30k and that works out to about 450µmols. That's about 50% of the light saturation point for cannabis. You were happy with the results at 30k lux and that's great. If you like how things are turning out, don't touch a thing.

So where's the 50% increase figure coming from?

Read on.

Research tells us that crop yield and quality increase in an almost linear manner as light levels increase, up to the light saturation point (the LSP is 800-1000µmols, depending on the strain). I've attached a paper that discusses this**.

I've created the table below, based on the formula in the paper.

The table was created using the formula for the yield curve and, in the PDF, I started the table at 600µmols because that's the minimum recommended amount for flowering cannabis.

What the table above indicates is that, in the plants that were grown for research, if the increase in yield between crops given 600µmols of light and 900µmols of light was 23.7%. Yup, by turning the lights from 600 to 900µmols, the crop yield would increase by almost 25%.

In the case of the grow that was at 450µmols vs that same grow at 900µmols, the increase in yield was 57±%.

You've taken the step of getting a light meter (I recommend the Uni-T Bluetooth meter or, if you want a PAR meter, I'd go with either an Apogee, a Li-Cor, or the Spot On). The next step is increase your light levels to hit a limit in the range of 800-1000µmols. Assuming that light was your limiting factor, your yield should increase significantly. Per the research, I would expect it to be somewhat more than 50%.


*I've been a software engineer for 30+ years, including three for Apple, so I have some insight into the software and hardware problems that he's dealing with. For a variety of reasons, I don't use Photone and I recommend it under only certain circumstances. I strongly recommend growers use a lux meter and get their grows to the light saturation point as quickly as possible.

**The Chandra paper, which shows that the curve starts to roll off at 500µmols is measuring net photosynthesis. The paper I've cited and attached deal with crop yield and crop quality.

@Delps8

The wafer in your Avatar looks almost ready for final test.

I must agree with @Delps8, give your plants as much light as they can handle as soon as possible. I do not use gauges (mostly out of stubbornness) but let the plant indicate when I am overdoing it. Too much light will start the edges of the leaf serration to begin to curl. Raise the light a couple of inches.

Something that is often not considered when speaking about DLI and/or PPFD is that the importance of those readings is dependent upon surface area, meaning leaf surface area. If you are counting the photons emitted by the light it does no good if you can't collect them.
More light = more energy = more roots = more vegetation = more transpiration = more nute consumption = more growth. And it starts all over again.

The following plant is 28 days old and seven inches tall. It will soon be allowed to grow vertically. It has received nearly 400 watts of light (six fixtures in a 2' x 3' cabinet) since it was four days old. It has also been fed 130% of recommended nutrient concentration (monitored by the tiny yellow tips of the leaves).

This technique averages 300 grams per plant (more than ten ounces). This is double what most growers on this site achieve per indoor plant, verifying what @Delps8 mentioned above.

 

[seaofgreen18]

Hmm... Must be the subject of the weekend, lol.

Lux = very poor way to measure light, unless you're planning your home interior lighting. It's weighted - and heavily so - towards the portions of the visible spectrum that appear brightest to the Mark I Eyeball, Human. Which isn't exactly the best portion of the spectrum for plants.

In theory, then, when comparing two lights of comparable efficiency and wattage, the one with the LOWER lux reading could just as easily be the most powerful grow light.

This has been common knowledge since well before "PAR" became an oft discussed topic, so part of me wants to question the judgment of anyone who has uploaded a video to YouTube recently (IOW, last few to several years at least) with a subject such as "plants are unable to use light above 45,000 LUX).

But, yeah, there is a maximum amount of light-energy that a plant can process at one time. And also in a day's time; see:

cannabis DLI

(DLI is an abbreviation for Day Light Integral, and plugging those the two terms into your favorite web-search engine ought to provide lots of information on the subject.)

Raising your garden temperature will help a bit. Doing so whilst adding CO₂ supplementation will help quite a bit in terms of how much light-energy your cannabis plants can effectively process. But there's still going to be an upper limit, otherwise enough light would allow us to literally watch them grow (into trees, lol).

Howdy well i do know to much light in flower will give the flowers a sun bleaching,turned them white as if they didn't get enough light but they were the tops and it wasn't from heat i Just my two cents folks oh and sometimes less is more!

 

[Hafta]

Howdy well i do know to much light in flower will give the flowers a sun bleaching,turned them white as if they didn't get enough light but they were the tops and it wasn't from heat i Just my two cents folks oh and sometimes less is more!

@seaofgreen18

You are absolutely correct. Not only will too much light turn them white, it can cause them to hermie.

The hermies tend to begin lower and on the older branches so if you see white, look for male flowers down below.
You can't guess how I know ..........

 

[seaofgreen18]

@seaofgreen18

You are absolutely correct. Not only will too much light turn them white, it can cause them to hermie.

The hermies tend to begin lower and on the older branches so if you see white, look for male flowers down below.
You can't guess how I know ..........

Lol that's funny! ive Done that to, Dont like to admit but , yeah! For me things like that need to happen so i can learn, a book or a pod cast really doesn't do much for me sometimes except get me in trouble lol!! I like too fuck with shit when things are good but ive gotten better by doing it but that's me