LED and Calmag issues.
- Thread starter 3rd Monkey
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Impregnant
Active Member
Formula for leafs: Vpsat
Where T is leaf Temperature in Celsius.
Formula for Room: VPair
Where T is air Temperature in Celsius and RH is Relative Humidity
VPD= (VPsat – VPair)
I had problems. Find out VPD. Tune mine not trying to feet charts. And oberved results.
You gonna dig a lot.
Where T is leaf Temperature in Celsius.
Formula for Room: VPair
Where T is air Temperature in Celsius and RH is Relative Humidity
VPD= (VPsat – VPair)
No no this is not what i was saying. There are no magic numbers.
I had problems. Find out VPD. Tune mine not trying to feet charts. And oberved results.
You gonna dig a lot.
Tetrahedral
Well-Known Member
I didn't want to get on the wrong side of the debate, the perfect condition for me is hot and dry. Our best Summers here are hot and dry, outdoors this favours the fast growing plants with less constraints on water. I would put cannabis in that group. If it's well watered it wants the fastest transpiration rate.
Not sure whether to dig up this old thread or start a new one. This was a frustrating read as I was hoping to find the cause of the problem, that I and others are having, but to no avail. My theory is that this is a spectral power distribution issue, which I believe translates to too much blue. But, I do not know. I'm ready to switch back to my old lights, but am hoping to find a solution with the ones I have, or try another LED that I'm sure would not be causing this.
My symptoms are mag deficiency, slow growth, drooping leaves about 4 hours prior to lights out with a 18/6 cycle.
Has anyone figured this out, or have any more light to shed on this issue?
My symptoms are mag deficiency, slow growth, drooping leaves about 4 hours prior to lights out with a 18/6 cycle.
Has anyone figured this out, or have any more light to shed on this issue?
NanoGadget
Well-Known Member
What are the Temps at the canopy?
80f. I've dialed in my VPD to about 83 ambient and 68% RH and it definitely helped. Plants perked up, but they still droop after 14 hours of day, and mag deficiency still there.
Honestly I think I'm fighting a losing battle. My lights are 4k CRI 90:
I feel like there is just too much of the spectrum.
cobshopgrow
Well-Known Member
hm, its strange.
up to 25% blue should be fine according to bugbee.
blue is responsible for telling the plant she needs to produce protective elements.
bugbee is trying to figure out the least amount needed of blue atm.
more then about 70% red in total is too much as the protective elements are missing.
this in short in my bad words, listen the recent podcast with him maybe.
to me its seems to be more a intensity problem.
i do prefer 26-28c for my small led grows, no co2 or else, but atm i get away well with about 24c day 20c night atm.
always nice green in veg too... this time.
edit: 4000k 90cri does look fine to me spectrum wise, there is really no extreme and its less then 25% blue.
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NanoGadget
Well-Known Member
Yeah, unfortunately I run 3k QB 288 v2 from seed to chop so I can't really comment on the effects that spectrum may be having, but I've seen people run some really unorthodox spectrums for full runs and I can't say that I've seen a particular plant pathology that was fully the result of spectrum. Also, 4k sits firmly in the middle of what has historically been considered effective for growing cannabis so it seems odd that spectrum alone would be causing so many issues. I'm sure the guys in the lab coats will pin this down sooner or later, but in the meantime I will say from personal experience that once I got my ambient Temps up into the low to mid 80s my apparent cal and mag issues went away.
cobshopgrow
Well-Known Member
most of the time above showen plant saw plain old 3000K 80cri as i wanted to see the effect a bit.
you can get the plant a bit more compact under higher kelivn temps, which is often good.
but 3000k 80cri gives you way more compact plants allready then a hps does, which is also fine for vegging some plants a bit.
true transpiration is key for calcium uptake, temp helps, while wonder that this time even below 23c all was fine, ok, i dont blast them really in veg with light, makes it all easier.
calcium nitrate, magnesium sulfate and i get them green.
you can get the plant a bit more compact under higher kelivn temps, which is often good.
but 3000k 80cri gives you way more compact plants allready then a hps does, which is also fine for vegging some plants a bit.
true transpiration is key for calcium uptake, temp helps, while wonder that this time even below 23c all was fine, ok, i dont blast them really in veg with light, makes it all easier.
calcium nitrate, magnesium sulfate and i get them green.
Is it clear to you from the graph that it is only 25%? Does it matter that the blue goes to 100% but the red never does? I know there is more red, but...
On the other hand I just looked at the graph for the samsung LM301b 4k and it looks similar to mine. But there's is CRI80 not 90. And most of the samsung products like HLG etc don't use straight (only) 4k do they? Most people don't run a 4k CRI90, so it is hard for me to know if it is something with that specific type.
At higher temp and humidity they do noticeably better, but still not good.
We run similar nutes. I've been foliar feeding them Epsom Salt (Magnesium Sulfate). And I increased the Calcium Nitrate. Do you think I should back off the cal nit?
Here is what they are looking like:
cobshopgrow
Well-Known Member
all below 5000k should be less then 25%.
the 100% is relative, the blue peak is quite small compared to the broader red.
compare the 80 and 90cri specra in the blux datasheet.
90cri have a shift towards red.
basically your light color temp should work fine.
HLG sells/sold a lot 4000K 80cri for veg if i am right.
your plants dont look too bad, but i hate the tiger stripes too.
your calcium nitrate seems to be fine, no tip burn or claws from the nitrogen to see.
the stripes are more the epsom.
foilar is quick, play a bit with what you just began, think that will help.
you maybe also can a bit heavier with the epsom in your feed.
i dont go higher with cal nitrate then 0.6g a liter.
the 100% is relative, the blue peak is quite small compared to the broader red.
compare the 80 and 90cri specra in the blux datasheet.
90cri have a shift towards red.
basically your light color temp should work fine.
HLG sells/sold a lot 4000K 80cri for veg if i am right.
your plants dont look too bad, but i hate the tiger stripes too.
your calcium nitrate seems to be fine, no tip burn or claws from the nitrogen to see.
the stripes are more the epsom.
foilar is quick, play a bit with what you just began, think that will help.
you maybe also can a bit heavier with the epsom in your feed.
i dont go higher with cal nitrate then 0.6g a liter.
Rurumo
Well-Known Member
Just from a past similar experience I had, I'd cut back the cal nit, and just feed some epsom salts for a few days. Then give it time to see if that worked. The older leaves won't improve so you need to wait for plenty of new growth. Don't go overboard with it, maybe do 1/4 t per gallon for a few days, then drop it to 1/4 t per 3-5 gallons for maintenance. You might not need it forever, as the plants get bigger and you raise the ppms of your base nutes, these issues have a way of disappearing. I think too much cal/mag or just straight cal is a big co-factor in a lot of the mag issues we see.
nobighurry
Well-Known Member
I have two tents and a flowering room, small tent for raising clones and seedlings, second tent is for veg, seedling tent has HLG V2, veg tent has HLG V1 and flower room has HPS & CMH, All in the same building, same temps, humidity & air, I had some girls that took way longer to finish then anticipated, so the girls in the veg tent with 4000k V1 vegged way longer then normal, I started seeing tiger stripes and some red stems, I applied cal mag and seen no improvement, I was able to move them into the flower room after two weeks and poof, the issues cleared right up, I have sence found I need to bump air temps up in veg tent 86f and add Epsom salt only to prevent the tiger stripes, I grow in coco and use 1 tbl of Epsom salt per gallon water, I am very new to LED (3yrs) and am no expert on them but that's what worked for my situation..
428grower
Well-Known Member
I was having these same issues with one of the LED i am running (mars hydro fc3000) but my Luxx 645 pro I’ve had zero issues with. I started spraying magnesium sulfate (epsom salt) once a week at a rate of 1tbsp per gallon and it seems to have taken care of the issue. It’s only 2 weeks but all the new growth is nice and green and no more drooping or slow growth. I do see what some people in here are talking about being correct like raising RH which I’m going to do here soon I just ordered a small humidifier.Edit: I’d like to add I dropped the power back to 50% on the light.
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428grower
Well-Known Member
You do 1tbsp per gallon and water it in?
twentyeight.threefive
Well-Known Member
That's the beginning of a magnesium deficiency not calcium.
Kushash
Well-Known Member
Yeah that looks like Mg.
I was in a comp using HPS against a large group of LED growers and we all had the same strain Adub x Animal Cookies and a # of us had Mg issues in early veg. I would say the plants we were growing were Mg whores. The 1st two signs to show up earliest in my opinion were purple stems and a light green overall plant color. This was in early veg, 1st two weeks from dropping the seeds. Some growers did get the more advanced yellowing between the veins like your plant is showing. When a mg deficiency shows up I'll add a small amount of epsom salt to the water being given to my soil (not sure if you are in soil) and also give an epsom foliar away from the lights. Mg deficiencies tend to be more common in veg than flower.
428grower
Well-Known Member
Maybe that is why I have not had any issues under the Luxx led because I flower under that one. I haven’t had any issues in flower but I have in veg.
nobighurry
Well-Known Member
Indeed 1tbl per gallon clears mag issue up rather quickly