LED and Calmag issues.

myke

myke

Well-Known Member
428grower said:
My plants are doing great now and all I changed was supplementing mag and sulfur with Epsom salt. I didn't do anything concerning changing humidity ot temperature.
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Plants look good. Amazing what a little Epsom will do. The grow stores will never tell ya though ha.
 
myke

myke

Well-Known Member
meangreengrowinmachine said:
They lose a lot of efficacy after 6 months to a year
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Well that’s why they say. But I’ve done side by sides years ago and I couldn’t tell the difference between new and used. Of course didn’t have a microscope to look at buds but to my eye buds were same size.
 
myke

myke

Well-Known Member
HPS lights also make a lot of heat for watts used. A 300 HPS makes a considerable more amount of heat then a same electricity heater. And the bonus is the de humidifier. So win win if your concerned about power use
 
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nobighurry

Well-Known Member
myke said:
HPS..... Heater and dehumidifier all in one.
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I absolutely agree I started with converted MH street lamps back in 1970s then HPS I kept hearing about the lack of heat from LEDs so I had to try one summer made sense vs AC running all day so after much prodding I gave leds a go there was a learning curve not huge but there I still use HPS & CMH during cold months using leds and running a heater just doesn’t pencil out imo
 
Three Berries

Three Berries

Well-Known Member
myke said:
I’m not sure if there the same bulbs but street lights used to be HPS and they went decades before change outs.
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With the vapor lights look at the inner bulb when off. They blacken over time, this is a indication of how it cuts the light output. HPS maintains it's output well, much better than MH. MH starts to loose output almost instantly.
 
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sweettooth

Active Member
jumping past the previous pages, never had calmag issues under led. the only issues I've had have been caused by too low temps, doesn't matter what your vpd is, ambient temps NEED to be 30 degrees or near. everytime my plants have looked rough under led, my temps have been too low. currently growing under a lumatek 600 and a maxibright 1030 using co2 at 1100ppm and running temps at 33 to 34 degrees, ec around 1.8 for 2nd week flower, rh around 72, plants look healthy and green. hps and mh give off IR so leaf temps will be higher than ambient temps, under led there is no IR so ambient temps need to be higher. get your temps sorted, you won't have deficiencies
 
Week4@inCharge

Week4@inCharge

Well-Known Member
3rd Monkey said:
So, there's been some correlation between using LED lights and calmag issues, particularly a lack of calcium and sometimes magnesium.

I've been doing some testing with tomato plants under an LED. I was finally able to replicate the issue.

Now, what I have found is that it's not really a Calmag issue at all, it's a potassium issue. Let me explain.

I ran 6 tomatoes under an LED until I got the issue to arise. I fed extra calmag to 2, dropped potassium to 1/2 and cut calmag in 2, and dropped potassium and calmag in 2 of them to 1/2.

The 2 with the extra calmag were fine until a full nute feeding, then back to calcium issues.

The 2 with reduced potassium and cut calmag, did better than full nutes and full calmag. Still issues.

The 2 with reduced potassium and barebones calmag seemed to alleviate the symptoms completely and are now growing healthy again.

I don't have lab equipment and I didn't document it, which I should have but had no idea what I was trying to do yet lol. However, in my testing, it appears that it's not a lack of calmag from the LED, but an excess of K.

I don't know if it deals with spectrum or par or whatever, but I would like some input from anyone who can possibly explain this, if it can be explained.
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Potash helps the ladies deal with the heat from the lamps.... same here, learned the hard way too....now I'm feeding heavy.. playing catch-up ..and once they get to that light color andor yellow ..damage is done... no turning back, just keep an eye on the remaining healthy ones. Leaned all this last week...lol.
 
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gforce3

Well-Known Member
Randomblame said:
The most nutrient issues we see with LED's are caused by a too high vapor pressure inside the leaves.
With HPS/MH or CMH bulbs the optimal ambient conditions are 25-26°C and 50-55% humidity cuz the heat radiation will heat up the leaf surface to ~28-30°C which is the optimal range for photosynthesis. These bulbs have up to 25% infra red in the range ~800nm. Plants are used to it cuz the sun has also IR and they use it to regulate certain processes like stomata breathing.
LED has no infra red and we need a higher ambient temperature to get the leaf surface temps in the optimal range. With LED ambient temps are = leaf surface temps(LST), with HPS it ambient +3°C.
Plants under strong LED light can not adjust the transpiration and we have to regulate it with ambient humidity to get the VPD in a healthy range.
But what has this to do with your calmag issues?
It is because when the humidity goes down the VPD inside the leaves get higher and the plants transpire more water than usual. With more water the plants also take up more nutes, especially calcium. And these high amounts of calcium looks out other metals like Mg, Fe, P and K. So yes, its because of calcium but because of too much nlt too little.

There are two ways to deal with it.
1. Lets say the VPD is 25% too high for the current plant stage. The plants transpire 25% more water and take up 25% more nutes. If you lower the ppms by 25% you can normalize the nutrient uptake but they can further use 25% more water.

2. the 2nd way to deal with it is to increase ambient humidity inside your grow room. The VPD is regulated by the relative humidity and the lower it is the higher the pressure to transpire water. With HPS and 25°C 50-55% is okay, with cold LED light and 28-30°C we need 60-65% humidity to keep the plants happy.
Below is a chart you can use.

Cutting nute strength and calmag in half worked out best because you did instictive No. 1. and have lowered the nutrient strength.

Its not so easy to maintain a good humidity the whole day. Especially in the dry month. A small atomizing humidifier just big enough for your room connected to a Sonoff TH switch timer(13$ incl. temp/humidity sensor) costs maybe 50$.

Indeed cannabis seems to need even more magnesium under strong LED light and too much calmag in the wrong moment(too high VPD) can make it even more worse. Plants would take up even more calcium this way.

Final conclusion...
It's actually no nutrient issue, it's a VPD issue caused by too low ambient humidity. Reduce your exaust fan or run it stop and go until the humidity is in the according range. Young plants and seedlings want 70-80% humidity(0,4-0,8kpa), plants in veg and early flowering want 60-70%(0,8-1,2kpa) and adult plants in the full flowering stage want 50-60% RH(1,2-1,6kpa).
The higher the VPD the higher the nutrient uptake and transpiration.
View attachment 4301464
I don't know your system but for your next nute soup I have following recommendation.
Add ~50ppm epsom salt to thw water first before you add your main fertilizer and if you have add some liquid silicone or horsetail extract too. Kelp, humidic acids, carbohydrates, myco's and other stuff can still be used but it would also work without such fancy stuff.
Pretty sure when you keep your VPD in a good range you don't need calmag. A bit more Mg in the normally used nutrient mix is already enough. Better two times too high humidity as one time too low.
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i know this is an old post but I finally found my problem thanks to you. My HPS side is healthy and beautiful. My LED side has been struggling and I’ve been pulling my hair out. I have been fighting what I thought was a cal deficiency and or k factor way longer than I should have. My vpd was barely hitting 1.6-1.7 in early flower and the plants were stressing and deficiency was showing.Temps were 78-80 degrees humidity was struggling to stay over 50-52%. Since then I added a humidifier and brought the relative humidity up to 60%-65% and bam my plants took off. Thank you, thank Jesus, and hallelujah!!!!
 
speedwell68

speedwell68

Well-Known Member
Flatrate said:
I've grown under LED for 2 years now and only add 2 grams per gallon of Epsom salt and never had a problem.
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I grew under HPS for years. I never gave Mg a second thought. When I came back to growing LEDs were all the rage and I started over with LEDs. I just grew them like I had with HPS and I got a massive Mg deficiency for my bother. I bought some Epsom salts and now I give them 2 teaspoons full per imperial gallon and they have been fine ever since.
 
Flatrate

Flatrate

Well-Known Member
speedwell68 said:
I grew under HPS for years. I never gave Mg a second thought. When I came back to growing LEDs were all the rage and I started over with LEDs. I just grew them like I had with HPS and I got a massive Mg deficiency for my bother. I bought some Epsom salts and now I give them 2 teaspoons full per imperial gallon and they have been fine ever since.
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I kinda started growing with LED, did my first trial run with CMH. I was lucky enough to somewhat get to know a grower on here at the time who knew a lot. He taught me to keep it simple and even shared his nute mixes with me. I use my tap that comes out around 7.5ph and 150ppm. All I use is 2 grams of Epsom per gallon and GH Micro, Grow, and Bloom. Never used Calmag and I get decent results.

tn_IMG_1194.JPG
 
Nutty sKunK

Nutty sKunK

Well-Known Member
rkymtnman said:
i'm about done with my first grow under QBs and my first Ca issues in a while.

my first thought is what is different about QBs vs cmh or hps or mh?

lack of infra-red. so people say run your garden warmer under leds to make up the difference.

maybe that is affecting the capillary action in the leaves which brings in less K. or maybe it brings in more K? and if you have too much Ca and a lessening of K, maybe that is part of the problem? or vice versa?
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You’re right in my experience. Had a nicely dialled in setup with Mh/HPS and soon as I switch to LED with the same temps ive
Got Ca issues in all my plants at almost all stages of growth.

Now my thinking is CMH during winter to make up for the cold temps. Otherwise I’m gonna need to spend more money on heating than lighting lol The LED i can use in the summer when I get can a steady 27-28c
 
G

gforce3

Well-Known Member
Nutty sKunK said:
You’re right in my experience. Had a nicely dialled in setup with Mh/HPS and soon as I switch to LED with the same temps ive
Got Ca issues in all my plants at almost all stages of growth.

Now my thinking is CMH during winter to make up for the cold temps. Otherwise I’m gonna need to spend more money on heating than lighting lol The LED i can use in the summer when I get can a steady 27-28c
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just add humidity and problem solved trust me . Keep your vpd at 1.2-1.6 and you will be happy.
 
PadawanWarrior

PadawanWarrior

Well-Known Member
Flatrate said:
I kinda started growing with LED, did my first trial run with CMH. I was lucky enough to somewhat get to know a grower on here at the time who knew a lot. He taught me to keep it simple and even shared his nute mixes with me. I use my tap that comes out around 7.5ph and 150ppm. All I use is 2 grams of Epsom per gallon and GH Micro, Grow, and Bloom. Never used Calmag and I get decent results.

View attachment 5013946
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I think I know who you're talking about, lol.

But to the OP: Intense lighting will demand more nutrients in general.
 
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sunsetdaydreamer

sunsetdaydreamer

Well-Known Member
sweettooth said:
jumping past the previous pages, never had calmag issues under led. the only issues I've had have been caused by too low temps, doesn't matter what your vpd is, ambient temps NEED to be 30 degrees or near. everytime my plants have looked rough under led, my temps have been too low. currently growing under a lumatek 600 and a maxibright 1030 using co2 at 1100ppm and running temps at 33 to 34 degrees, ec around 1.8 for 2nd week flower, rh around 72, plants look healthy and green. hps and mh give off IR so leaf temps will be higher than ambient temps, under led there is no IR so ambient temps need to be higher. get your temps sorted, you won't have deficiencies
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Hey, do you have pictures of your plants?
 
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