problems with quantum boards(yellowing)

[Only The Best]

hi icmagers

this is my first grow with leds(quantum boards).i have 1 sf4000 from spider farmer and 1 v3 480w from kingbrite.the plants are 1 month old and my problem start from the beginning.
i read a lot about the feeding in leds and especially in qb,..thats why first time, since i begin to grow,i bought cal mag.
the plants are in a rdwc system that holds 150 litres of water.
ec 1,2 (with 150ml of cal mag)
ph 5,5-6
water temp 21c
tent temp 27-28c
humidity 53%

all the plants are pal yellow and lately some leaves turning brown and crispy.

i broke my head to find what is wrong but i cant find the reason.
please help me
i was so exciting with my new toys (the leds) and now i very dissapointed.

 

[Only The Best]

some more

 

[Cantharellus]

I just switched to LED beginning of the year. I decided to not do anything different and see what happened. So far everything has been pretty good. The plants are not as deep a green as before. I would try to go back to what worked for you and then try to adjust if you see a problem. I have never used cal mag in 30 years of indoor.

 

[bigpeter]

How high are your lights? I started mine at 80 cm under sf2000 and it grew very well.

 

[DARKSIDER]

hi icmagers

this is my first grow with leds(quantum boards).i have 1 sf4000 from spider farmer and 1 v3 480w from kingbrite.the plants are 1 month old and my problem start from the beginning.
i read a lot about the feeding in leds and especially in qb,..thats why first time, since i begin to grow,i bought cal mag.
the plants are in a rdwc system that holds 150 litres of water.
ec 1,2 (with 150ml of cal mag)
ph 5,5-6
water temp 21c
tent temp 27-28c
humidity 53%

all the plants are pal yellow and lately some leaves turning brown and crispy.

i broke my head to find what is wrong but i cant find the reason.
please help me
i was so exciting with my new toys (the leds) and now i very dissapointed.

View Image

View Image

View Image

View Image

View Image

Hope you get this fixed ive just moved on to leds too so not much too offer realy but hopefully this chart may help a little

 

[chiesesganja]

check root aphid
i think u can try to turn low the ec about 0,8-1 i think 1.2 is too much for veg....
if ur not use ro water then no need the calma

 

[SuperBadGrower]

RO or tap?
Does 1.2 EC include ca/mg?


Tap water:
Possibly high Ca can lock out K and Mg.
My ca/mg product has 4:1 ca:mg. However it seems unlikely to me. The plants don't look deep green or overfed in any other ways.

Check your base nutrient Mg content. My A&B only has 15 ppm Mg, which has some plants starving.
If tap (0.3-0.4 EC) the nutrients are low IMO, on RO I guess 1.2 should be OK. Ca/mg on top of that to 1.4 EC.

But I bet you were using this without problems first. So I would agree to go back to your normal recipe and go from there.
Your temps are good. Should be no issue at all.

Outside of that kind of stuff, the obvious conclusion is simply too much light that the plant cant handle. How much w are you using in veg total? (Did you swap out hids watt for watt?) Are you dimming the lights? Do you have some kind of lux meter to approximate light intensity?

If you vegged under MH or T5, just forget everything. Those lights put out even less light than HPS in terms of µmol/j. Lets say you can replace a 1000w DE with about 600w of LED and you still get about the same light. For DE 1kw HPS you calculate 1.7 µmol/j. For a 1kw MH you can calculate 0.85 µmol/j.

So someone who used 400w of MH to veg can replace it with 130w of leds. If you go higher than 150w you'll probably start seeing issues that are related to a higher light intensity. Maybe not because the light is too intense of itself, but because the user's system is not geared for a high light intensity veg. (Up to 400 µmol/m²/s)

Source:
https://www.lrc.rpi.edu/programs/energy/pdf/HorticulturalLightingReport-Final.pdf


I cant back this up empirically but I think diffuse lighting needs even lower light intensity than point source(s). Every part of the plant gets 200µmol/s; with these spread out leds, there are very few shadows and light bounces from many directions. With HID many leaves are comfortably shaded reducing the total light the plant sees.

 

[TanzanianMagic]

Because of the extent of the damage to the edge of the leaves, I would say potassium deficiency/lockout. Maybe magnesium. Both are mobile nutrients that are locked out at a low pH. Or, they could be in high demand, and something is locking out nutrients from the root system.

I would check out the roots, and maybe lower the temperatures in the room. If the max temperature is 28C, temp at foliage level is going to be higher, even with LEDs. And perhaps 21C for the reservoir is too high.

 

[Only The Best]

I just switched to LED beginning of the year. I decided to not do anything different and see what happened. So far everything has been pretty good. The plants are not as deep a green as before. I would try to go back to what worked for you and then try to adjust if you see a problem. I have never used cal mag in 30 years of indoor.

i dint do anything different either,also i have never used cal mag since i begin to grow 15 years..

How high are your lights? I started mine at 80 cm under sf2000 and it grew very well.

my lights are 70cm about high.

Hope you get this fixed ive just moved on to leds too so not much too offer realy but hopefully this chart may help a little

hey bro thanks for the photo,im really sad because i dont know what to do.

check root aphid
i think u can try to turn low the ec about 0,8-1 i think 1.2 is too much for veg....
if ur not use ro water then no need the calma

definately is not root aphid and i use RO water so my ec is on the right level.

RO or tap?
Does 1.2 EC include ca/mg?


Tap water:
Possibly high Ca can lock out K and Mg.
My ca/mg product has 4:1 ca:mg. However it seems unlikely to me. The plants don't look deep green or overfed in any other ways.

Check your base nutrient Mg content. My A&B only has 15 ppm Mg, which has some plants starving.
If tap (0.3-0.4 EC) the nutrients are low IMO, on RO I guess 1.2 should be OK. Ca/mg on top of that to 1.4 EC.

But I bet you were using this without problems first. So I would agree to go back to your normal recipe and go from there.
Your temps are good. Should be no issue at all.

Outside of that kind of stuff, the obvious conclusion is simply too much light that the plant cant handle. How much w are you using in veg total? (Did you swap out hids watt for watt?) Are you dimming the lights? Do you have some kind of lux meter to approximate light intensity?

If you vegged under MH or T5, just forget everything. Those lights put out even less light than HPS in terms of µmol/j. Lets say you can replace a 1000w DE with about 600w of LED and you still get about the same light. For DE 1kw HPS you calculate 1.7 µmol/j. For a 1kw MH you can calculate 0.85 µmol/j.

So someone who used 400w of MH to veg can replace it with 130w of leds. If you go higher than 150w you'll probably start seeing issues that are related to a higher light intensity. Maybe not because the light is too intense of itself, but because the user's system is not geared for a high light intensity veg. (Up to 400 µmol/m²/s)

Source:
https://www.lrc.rpi.edu/programs/energy/pdf/HorticulturalLightingReport-Final.pdf


I cant back this up empirically but I think diffuse lighting needs even lower light intensity than point source(s). Every part of the plant gets 200µmol/s; with these spread out leds, there are very few shadows and light bounces from many directions. With HID many leaves are comfortably shaded reducing the total light the plant sees.

i use ro water and general hydroponics fertilizers,also the cal mag is general hydroponics.i thought after some reading in the web that after the cal mag my problem will be gone but unfortunately
getting worse.the only think i change is the lights and the cal mag i add in the system.
i started believe that my intence light is my problem,the plants in
the photo are 5 days in 12/12 and i veg them with 2 quantum board at max power which means 900w.yesterday i lowered i little the one qb and i ordered a dimmer for the other one.
its a same because i had a lot expectasion for these light and i nevered see my plants suffer so much

 

[bigpeter]

What medium are you using in your RDWC, I read through your posts and cant see any obvious mistakes. Sounds stupid question but is your ph meter calibrated?

 

[jaded1]

Looks like lights are too close and plants cant keep up with the amount of light coming at them.Is a prob lots have when 1st using these qb type led's.I find about 20" above the plants is the sweet spot with mine(not the same as yours).

 

[SuperBadGrower]

i started believe that my intence light is my problem,the plants in
the photo are 5 days in 12/12 and i veg them with 2 quantum board at max power which means 900w.yesterday i lowered i little the one qb and i ordered a dimmer for the other one.
its a same because i had a lot expectasion for these light and i nevered see my plants suffer so much

Yeah, sounds like its the light intensity.

What's your footprint there. Looks like a 4*8 tent (120*240cm)?

If so, the 900 watts should be good for flower. It's definitely overkill for veg, such leaf damage is no surprise.

Look on the 'bright' side They only suffer because there is so much light (if this diagnosis is correct)

Maybe the light level is adequate but high* (<500 or <450 µmol/s). In that case raising nutrients may also be a solution. (Literally and figuratively) But like I said, I would continue doing things as you always did, just with lower light intensity (at least in veg). that should start you off from a clean slate. Later you can always try to increase intensity or feed once you have green praying plants.

* I doubt it, since the damage is so profound

edit: Maybe consider giving them a few "bad days" (like cloudy in nature), but in flower I would get them back on the full intensity in/after week 3

 

[Only The Best]

What medium are you using in your RDWC, I read through your posts and cant see any obvious mistakes. Sounds stupid question but is your ph meter calibrated?

i use clay pebbles and my ph meter is calibrated..propably
my mistake is the power of the lights.

Looks like lights are too close and plants cant keep up with the amount of light coming at them.Is a prob lots have when 1st using these qb type led's.I find about 20" above the plants is the sweet spot with mine(not the same as yours).

the lights are not close if you see the pic with the lights,but are working at full power.

Yeah, sounds like its the light intensity.

What's your footprint there. Looks like a 4*8 tent (120*240cm)?

If so, the 900 watts should be good for flower. It's definitely overkill for veg, such leaf damage is no surprise.

Look on the 'bright' side They only suffer because there is so much light (if this diagnosis is correct)

Maybe the light level is adequate but high* (<500 or <450 µmol/s). In that case raising nutrients may also be a solution. (Literally and figuratively) But like I said, I would continue doing things as you always did, just with lower light intensity (at least in veg). that should start you off from a clean slate. Later you can always try to increase intensity or feed once you have green praying plants.

* I doubt it, since the damage is so profound

edit: Maybe consider giving them a few "bad days" (like cloudy in nature), but in flower I would get them back on the full intensity in/after week 3

you are my man..i bet that the light intensity is my problem.
i have steady ec couple days which means my plant dont eat their food.everything else, as i told,is on schedule expept the lights..
today i lowered the power -i dont know how much because i dont have kill a watt-and i will give them some cloudy days,i hope they recover.how many days i will wait for recovering?
my tent is 2,4m X 1,2m as you said.
thanks

 

[SuperBadGrower]

What kind of drivers do those lights use? Most Meanwell HLG drivers dim the current to 50% - so, if you turn the knob all the way down on a 240w driver you are giving 120w.

Some drivers dim to 0% (ELG series). If you turn the knob all the way down on those, the light shuts off.

If your light dims but still gives respectable light on the lowest setting, it's probably at 50%.

Since you are into flower now, they should be able to handle the 12 hours of full intensity. High intensity is only a problem over time To piece some of this information together, look again at "DLI". The sun can give 2000µmol/s, but only temporarily. (Not all day long)

However, since they are a bit stressed and damaged, some "easy days" can really help that new growth. But I would not dim it too much, for too long. Going in week 4 you definitely want the full intensity. By then they will still have the damaged leaves, but healthy and vigorous new growth (hopefully). That might already be the case by now after long nights.

I would do this: Dim to a little above 50% for a few days, examine the new growth and go from there. After 2 days you should be seeing a difference in the stature of the plant. If the new growth is properly colored and expanded and the plant looks more perky, resume with full intensity.

 

[Kalbhairav]

The same happened to me when I used QBs.

Lights for optimum PAR should be around 40-35cm from canopy.

LEDs seem to make plants absolutely drink/eat Mg. what I’m seeing from your pictures is Mag def! Add a Epsom salts or CalMag depending on which way you lean.

You might find you have to add with every feeding to get them back to shiny green.

Mg supports N in transmission to the growing points. The high intensity of QBs mean that Mg is more readily needed to keep your plants healthy.

Believe it or not, this is a common problem when using QBs.

Just to add, it might be beneficial to add iron as well as trace elements as well. Sorry I haven’t read the entire thread so don’t know how you’re feeding.

 

[Only The Best]

What kind of drivers do those lights use? Most Meanwell HLG drivers dim the current to 50% - so, if you turn the knob all the way down on a 240w driver you are giving 120w.

Some drivers dim to 0% (ELG series). If you turn the knob all the way down on those, the light shuts off.

If your light dims but still gives respectable light on the lowest setting, it's probably at 50%.

Since you are into flower now, they should be able to handle the 12 hours of full intensity. High intensity is only a problem over time

To piece some of this information together, look again at "DLI". The sun can give 2000µmol/s, but only temporarily. (Not all day long)

However, since they are a bit stressed and damaged, some "easy days" can really help that new growth. But I would not dim it too much, for too long. Going in week 4 you definitely want the full intensity. By then they will still have the damaged leaves, but healthy and vigorous new growth (hopefully). That might already be the case by now after long nights.

I would do this: Dim to a little above 50% for a few days, examine the new growth and go from there. After 2 days you should be seeing a difference in the stature of the plant. If the new growth is properly colored and expanded and the plant looks more perky, resume with full intensity.

hi SBG
my drivers are HLG.since i found that my problem is the light i lowered the power of the lights..but i dont see any progress,the plants remain yellow and they dont eat nutrients..im on 15 days 12/12.

The same happened to me when I used QBs.

Lights for optimum PAR should be around 40-35cm from canopy.

LEDs seem to make plants absolutely drink/eat Mg. what I’m seeing from your pictures is Mag def! Add a Epsom salts or CalMag depending on which way you lean.

You might find you have to add with every feeding to get them back to shiny green.

Mg supports N in transmission to the growing points. The high intensity of QBs mean that Mg is more readily needed to keep your plants healthy.

Believe it or not, this is a common problem when using QBs.

Just to add, it might be beneficial to add iron as well as trace elements as well. Sorry I haven’t read the entire thread so don’t know how you’re feeding.

hi Kalbhairav

my lights are at 70cm from the canopy and still have problem.
i gave mg but i dont see any different yet...im on the second week of flower and i dont know if is good to give them some N.
Why you stopped using QBs?

 

[Kalbhairav]

hi Kalbhairav

my lights are at 70cm from the canopy and still have problem.
i gave mg but i dont see any different yet...im on the second week of flower and i dont know if is good to give them some N.
Why you stopped using QBs?

Hi,

Light height is fine then

How much Mg did you give them per litre? Your plants need a lot, plus iron and trace elements. Sometimes Mg and iron deficiency look the same.

Did your plants start off losing colour like the picture of the plant below?

This is a picture of my Northern Lights under the QB. This was the start of a Mg and (maybe) an iron deficiency. I corrected it by adding CalMag for every watering until the problem disappeared, and it took a while. I don’t like using mineral CalMag and have since found an organic substitute. At the time I knew I had to fix the problem fast. The brand I used had Mg, Cal, Iron plus trace elements.

Your plants still need N during flower. When the plant transitions from vegetative growth to flowering, you should still be feeding Nitrogen feed so the plant has enough throughout flower, at least two weeks into the flowering period depending on variety. I found my plants under QBs needed more. I had to completely change my feeding regime under QBs!

I’m no longer using QBs because I wanted something more powerful and opted for single led cob units that I could have at different heights depending on plant height.

I’m still not sure what medium you’re using as I haven’t read the entire thread. I grow organically in soil and the above worked for me. If you’re hydro or coco then your problems might be PH/nutrient lockout.

 

[SuperBadGrower]

Hmm I never used RWDC so I don't know much about what normally happens. if the plants take no nutrients at all but the water level decreases, then the EC should rise, right?

Indeed, if adjusting the light by itself hasn't fixed the problem to your eyes, it could be the case that your old nutrient strength is simply not doing the job.

Great post Kalbhairav.

As far as EC, I understand many people in RWDC use a low EC and find that the plants drink more the lower they go. EC doesn't tell evertyhing though. Even at 2 EC some A&B may not have enough Mg.

Whats happening now is a complex interaction between light intensity, leaf temperature, nutrient strength, etc.
Difficult to trouble shoot in a short time You will find the way

My feed in flower has even more nitrogen than veg, and still, this happens.

According to the bro science that plant should be dark green, combust to 100% black ash and be unsmokable .

I grow much higher EC but don't do DWC...1.2 sounds low to me, but since you have had success with it, I'm not one to comment
I wouldn't expect the old big leaves to green up quickly, but the new growth should look green & vigorous

 

[MindEater]

Leds are trash, throw them in the dumpster. Tried everything, the plants simply won't uptake nutes properly.

 

[GMT]

Kalbhairav nailed it. The plants want to grow quickly under led, so they canabalise the nitrogen from the bottom shaded leaves. People reach for the cal mag to aid in that, but forget the iron. Either give them more nitrogen, add some iron to the cal mag, or raise the lights so they don't grow as quickly. Any of those will help a lot. I'm still feeling my way around led too, so there may be other solutions yet. Oh I suppose you could turn the light power down too and save some electric.