Newbie needing help diagnosing spots on leaves!

[Lovie]

You are using two Vivosun's 200W AeroWing SEs lights in a 4x4 tent? 400 wats / 16 square foot is 25 wat/square foot. You have plenty of light to flower. Adding 80 wats would take you to to peak yield performance if you could even out the coverage. 800 to 1500 PPFD is the max range in flower. I do seriously question there PPFD chart with the highest numbers being under the center fan where there are no lights.

I was basing that comment on what the Photone App said. I read it is most accurate on Apple products with a diffuser so I downloaded it on my stepdaughter's phone since she is the only one here that uses Apple products and tested it. According to the Photone App my lights at 100% intensity 12 inches away from the center of the light only had a PPFD of 450. I am not about to dish out $400 for a PAR meter. I did read you can get a Lux meter for cheap and with some math be able to calculate the PAR.....so maybe I will try that. From what I have read the PAR maps provided by light manufacturers are normally off.

I have been using my lights at 85% intensity already.....I have had no stretching or signs of bleaching, so I assume they are in a good range for now. I lowered the intensity to 80% since I lowered the lights, but I am thinking if I am already at 80% intensity for veg that 100% will not be enough for flower.

 

[Trump]

I was basing that comment on what the Photone App said. I read it is most accurate on Apple products with a diffuser so I downloaded it on my stepdaughter's phone since she is the only one here that uses Apple products and tested it. According to the Photone App my lights at 100% intensity 12 inches away from the center of the light only had a PPFD of 450. I am not about to dish out $400 for a PAR meter. I did read you can get a Lux meter for cheap and with some math be able to calculate the PAR.....so maybe I will try that. From what I have read the PAR maps provided by light manufacturers are normally off.

I have been using my lights at 85% intensity already.....I have had no stretching or signs of bleaching, so I assume they are in a good range for now. I lowered the intensity to 80% since I lowered the lights, but I am thinking if I am already at 80% intensity for veg that 100% will not be enough for flower.

If it hasn't been mentioned before, read up on how to use Daily Light Integral(DLI)

I've found it to be much easier in regard to where I want to set my light intensity at.

The Daily Light Integral of Plants

The daily light integral (DLI) specifies the usable light received within a 24 hour window. Understanding and optimizing DLI is crucial for healthy plants and bountiful plant yield.

growlightmeter.com

 

[Lovie]

If it hasn't been mentioned before, read up on how to use Daily Light Integral(DLI)

I've found it to be much easier in regard to where I want to set my light intensity at.

The Daily Light Integral of Plants

The daily light integral (DLI) specifies the usable light received within a 24 hour window. Understanding and optimizing DLI is crucial for healthy plants and bountiful plant yield.

growlightmeter.com

I have not, but I will. Thank you!

 

[SmokingWings]

400 wats / 16 square foot is 25 wat/square foot. You have plenty of light to flower.

I was under the impression that it was a minimum of 35 watts per square foot for the vegetative stage and more for flowering if possible.

 

[bluter]

I was under the impression that it was a minimum of 35 watts per square foot for the vegetative stage and more for flowering if possible.

a lot of the newer rigs are above the 35w/sqft efficiency now. you have to stick with a decent brand and a quality rig to do it though. they are not all created equal.

 

[Sativa1970]

Your plant is the most accurate light meter you can use. With hundreds of strains and grow conditions there is a magic number but your plant is only one that knows it. Your max tolerated light in veg is just over the minimum light in flower. Close nodes with no light burn shows you are in an optimum PPFD range for veg. You need 20 to 30% more light in flower. If you can lower lights and turn the dial up 20% you are ok.

This is the wat/ square foot ratio that I found over several strains.
Below 15 wats buds are low cannabinoid and too fluffy to bother smoking.
At 15 wats low potency and yield but buds will mature to a useful level. For example .5 oz.
At 20 wats full potency and double the 15 wat yield with denser buds. For example 1 oz
At 25 wats yield increases half as much again and bud density increases. For example 1.5 oz
At 30 wats yield increases by a fourth buds increase density again. For example 1.75 oz
At 35 wats peak yield and density without CO2 enrichment. For example 2 oz

I was under the impression that it was a minimum of 35 watts per square foot for the vegetative stage and more for flowering if possible.

I am referring to average LED at 1 foot and it is a rough translation to PPFD. HIDs, blurples or changing the height would be a completely different scale. It's also important to remember that plants are just a chemical reaction. The lowest denominator of your reactants( minerals, O2,CO2 and water) or catalysts ( photons and temp) will determine the product of the reaction (sugars). Anything over 25wats in veg is just diminishing returns and added heat. Same with over 35 wats in flower. CO2 becomes the limiting reactant when increasing from 35 to 40 wats. You may gain 5% yield with atmospheric CO2.

 

[Trump]

Your plant is the most accurate light meter you can use. With hundreds of strains and grow conditions there is a magic number but your plant is only one that knows it. Your max tolerated light in veg is just over the minimum light in flower. Close nodes with no light burn shows you are in an optimum PPFD range for veg. You need 20 to 30% more light in flower. If you can lower lights and turn the dial up 20% you are ok.

This is the wat/ square foot ratio that I found over several strains.
Below 15 wats buds are low cannabinoid and too fluffy to bother smoking.
At 15 wats low potency and yield but buds will mature to a useful level. For example .5 oz.
At 20 wats full potency and double the 15 wat yield with denser buds. For example 1 oz
At 25 wats yield increases half as much again and bud density increases. For example 1.5 oz
At 30 wats yield increases by a fourth buds increase density again. For example 1.75 oz
At 35 wats peak yield and density without CO2 enrichment. For example 2 oz


I am referring to average LED at 1 foot and it is a rough translation to PPFD. HIDs, blurples or changing the height would be a completely different scale. It's also important to remember that plants are just a chemical reaction. The lowest denominator of your reactants( minerals, O2,CO2 and water) or catalysts ( photons and temp) will determine the product of the reaction (sugars). Anything over 25wats in veg is just diminishing returns and added heat. Same with over 35 wats in flower. CO2 becomes the limiting reactant when increasing from 35 to 40 wats. You may gain 5% yield with atmospheric CO2.

Are you saying that the max light exposure that the plants can take up is 25w in veg and 35w in flower using their respective time frames of 18/6 and 12/12? Would you say that this corresponds to DLI chart levels?

 

[bluter]

Your plant is the most accurate light meter you can use. With hundreds of strains and grow conditions there is a magic number but your plant is only one that knows it. Your max tolerated light in veg is just over the minimum light in flower. Close nodes with no light burn shows you are in an optimum PPFD range for veg. You need 20 to 30% more light in flower. If you can lower lights and turn the dial up 20% you are ok.

This is the wat/ square foot ratio that I found over several strains.
Below 15 wats buds are low cannabinoid and too fluffy to bother smoking.
At 15 wats low potency and yield but buds will mature to a useful level. For example .5 oz.
At 20 wats full potency and double the 15 wat yield with denser buds. For example 1 oz
At 25 wats yield increases half as much again and bud density increases. For example 1.5 oz
At 30 wats yield increases by a fourth buds increase density again. For example 1.75 oz
At 35 wats peak yield and density without CO2 enrichment. For example 2 oz


I am referring to average LED at 1 foot and it is a rough translation to PPFD. HIDs, blurples or changing the height would be a completely different scale. It's also important to remember that plants are just a chemical reaction. The lowest denominator of your reactants( minerals, O2,CO2 and water) or catalysts ( photons and temp) will determine the product of the reaction (sugars). Anything over 25wats in veg is just diminishing returns and added heat. Same with over 35 wats in flower. CO2 becomes the limiting reactant when increasing from 35 to 40 wats. You may gain 5% yield with atmospheric CO2.

currently run flower with 600w in 4 x 4 - 37.5 w/sqft. going to 650w soon - 40w/sqft. i use active dimming though and never get above 90% on anything.
found it's better to have the power and coverage and not need it, than need power and coverage and not have it.

 

[Sativa1970]

Are you saying that the max light exposure that the plants can take up is 25w in veg and 35w in flower using their respective time frames of 18/6 and 12/12? Would you say that this corresponds to DLI chart levels?

Wats per square foot is just a general guide. Yes 25 veg and 30 flower puts you in the best yield per photon area. Generally 30 veg and 35 flower is near max saturation. Shooting for the peak of a bell curve not the top 1%. Light efficiency, grow room efficiency, and length of day are going to impact this estimate even more. Since we don't trust the PPFD of the manufacturer or the meter, it's the next best thing to get in the ballpark. Wats to DLI is comparing a ruler to a micrometers measurements. The margin of error makes the answer useless.

If all other factors are optimal and you are going for absolute highest growth rate then yes you can increase the lighting over that wat estimate. Most of us are not growing under lab controlled conditions. Hell, we are currently using wats instead of PPFD readings. We don't have the equipment or controls to even quantify a few % better grow.

I am referencing roughly what you need to grow. You are asking bought an optimized grow.

 

[Trump]

Wats per square foot is just a general guide. Yes 25 veg and 30 flower puts you in the best yield per photon area. Generally 30 veg and 35 flower is near max saturation. Shooting for the peak of a bell curve not the top 1%. Light efficiency, grow room efficiency, and length of day are going to impact this estimate even more. Since we don't trust the PPFD of the manufacturer or the meter, it's the next best thing to get in the ballpark. Wats to DLI is comparing a ruler to a micrometers measurements. The margin of error makes the answer useless.

If all other factors are optimal and you are going for absolute highest growth rate then yes you can increase the lighting over that wat estimate. Most of us are not growing under lab controlled conditions. Hell, we are currently using wats instead of PPFD readings. We don't have the equipment or controls to even quantify a few % better grow.

I am referencing roughly what you need to grow. You are asking bought an optimized grow.

But you're claiming that these numbers are peak for best yield. That would suggest that these aren't rough estimates but solid standards in normal conditions. If these numbers are best by your account anything else would be outside of "best" range. Your numbers would also inform anyone buying a light to not go beyond your numbers as that would take them outside of the "best" range and be a waste of photons unless they plan on running CO² that benefits from higher temps and PPFD.

You stated that these numbers are relative to the other conditions you posted but that would suggest that there really isn't an actual number or range that could be labeled as "best" because "best" depends on the other factors you listed.

DLI does more or less the same thing you are posting in that it suggests a maximum amount of photons that the plants can absorb in a given day.

I agree that each cultivar dictates its own "ideal" conditions by how they react to our inputs. I run my grows by what the plants tell me rather than try and run by the numbers.

 

[Lovie]

I was under the impression that it was a minimum of 35 watts per square foot for the vegetative stage and more for flowering if possible.

 

[Lovie]

FYI...after reading this I have decided not to try the UV lighting for now.

Indoor grown cannabis yield increased proportionally with light intensity, but ultraviolet radiation did not affect yield or cannabinoid content - PMC

Cannabis (Cannabis sativa) flourishes under high light intensities (LI); making it an expensive commodity to grow in controlled environments, despite its high market value. It is commonly believed that cannabis secondary metabolite levels may be ...

www.ncbi.nlm.nih.gov

It's a hard read. It does mention that the experiment should be conducted again using parameters that better matches the sun's output of UV to see if there could be a benefit from using UV. However, based on their experiment, it did not have a significant benefit.

 

[Trump]

FYI...after reading this I have decided not to try the UV lighting for now.

Indoor grown cannabis yield increased proportionally with light intensity, but ultraviolet radiation did not affect yield or cannabinoid content - PMC

Cannabis (Cannabis sativa) flourishes under high light intensities (LI); making it an expensive commodity to grow in controlled environments, despite its high market value. It is commonly believed that cannabis secondary metabolite levels may be ...

www.ncbi.nlm.nih.gov

It's a hard read. It does mention that the experiment should be conducted again using parameters that better matches the sun's output of UV to see if there could be a benefit from using UV. However, based on their experiment, it did not have a significant benefit.

IMO, optimize what you have now. I've been reading about UV for years now but have never really seen increases vs something like adding CO². If you feel you've already gotten there then do side by sides to see if it's worth it. For me, it just adds more complication for little return. The full spectrum lights they sell nowadays usually has a few UV diodes in them.

 

[Sativa1970]

But you're claiming that these numbers are peak for best yield. That would suggest that these aren't rough estimates but solid standards in normal conditions. If these numbers are best by your account anything else would be outside of "best" range. Your numbers would also inform anyone buying a light to not go beyond your numbers as that would take them outside of the "best" range and be a waste of photons unless they plan on running CO² that benefits from higher temps and PPFD.

You stated that these numbers are relative to the other conditions you posted but that would suggest that there really isn't an actual number or range that could be labeled as "best" because "best" depends on the other factors you listed.

DLI does more or less the same thing you are posting in that it suggests a maximum amount of photons that the plants can absorb in a given day.

I agree that each cultivar dictates its own "ideal" conditions by how they react to our inputs. I run my grows by what the plants tell me rather than try and run by the numbers.

I will try to explain this one last time because we are off in the weeds here.. The OP was told his plants would not flower under his lights. Manufacturers PPFD chart is obviously wrong when it shows highest numbers where there are no LEDs. Phone app is no where near what the PPFD range could possibly be. Unfamiliar grow room, new strain, so the only useful data we have left is wats. Absolutely not a fine science but working with what we got.

Wats will give you a rough range of photons at the LED. Distance and reflection will give you a range of photon intensity at the plant. Environment gives a range of what a plant can absorb. The cultivar will give a range of what the leaf can absorb. If you average out all of the variables the wats I listed are an accurate guide. Blurple lights 3 feet way, no walls, equatorial strain, CO2 tanks, so forth, or anything outside of average will skew the estimated wattages I gave.

Can you get a better yield with more light? yes. Will most yield double from 15 to 20 wats? most likely, Yes. Will most yield double going all the way from 30 to 40 wats? Most likely not. 30 wats puts you in the 800PPFD range and 35wats close to 1000PPFD. Growth rate is no longer linear after 800PPFD. The reason for the drop off in growth is CO2 demand. Growth rate doesn't stop at 800 it slows exponentially because there is insufficient atmospheric CO2 for the increased in reaction rate. Applying more lights and power will only show diminishing gains in yield. I am defining best by yield per wat efficiency on an average. I think your definition of best is absolute ideal max yield, no matter the price. By that definition of best, then you are correct.

Wats are like engine RPMs, PPFD is actual MPH, and DLI is how far you traveled in a day. All related but you can not accurately determine the odometer reading from just watching a tachometer. But you can make an educated guess.