LED and Calmag issues.

ChiefRunningPhist

ChiefRunningPhist

Well-Known Member
3rd Monkey said:
Yea, that's what I gathered as well.

Basically, my running theory is that LEDs increase the potency or uptake of K in the plant, reducing overall Ca values taken in.

I don't have the room to set up a proper testing ground at the moment, but I would like to evaluate this further.
Click to expand...
Well when you get it figured out just lmk lol
 
3rd Monkey

3rd Monkey

Well-Known Member
How does this sound as far as a control?

Found some cheap Jacks classic 20-20-20 online. Use that as a baseline. Doesn't contain calcium.

Then I can use calmag and a K feed to adjust, this way it's an even base with only 2 factors.

Does that sound ok, or should I do something else?
 
jarvild

jarvild

Well-Known Member
3rd Monkey said:
How does this sound as far as a control?

Found some cheap Jacks classic 20-20-20 online. Use that as a baseline. Doesn't contain calcium.

Then I can use calmag and a K feed to adjust, this way it's an even base with only 2 factors.

Does that sound ok, or should I do something else?
Click to expand...
If your using coir with compost and teas you need to watch out for K-tox as coir releases K as it decomposes. Addition of bacteria from the compost and tea helps speed the process up.
 
3rd Monkey

3rd Monkey

Well-Known Member
jarvild said:
If your using coir with compost and teas you need to watch out for K-tox as coir releases K as it decomposes. Addition of bacteria from the compost and tea helps speed the process up.
Click to expand...
I've grown like this for a while with no issues?

Not saying I don't believe you, just that I've never had this issue. Something I will have to investigate.

That fucks my control. I can't go hydro with the power here, in and out.

Any suggestions?
 
rkymtnman

rkymtnman

Well-Known Member
budman111 said:
Yes, catches out the most seasoned grower mid-bloom if not foretold about the issue and will kill the plant within a week if untreated .
Click to expand...
luckily i caught it after just 2 days. a full dose of cal/mg stopped it in its' tracks.

so you think a good solution is to just add cal/mg after the stretch is over? any idea of what ppm value i should be targeting for total Ca?
 
budman111

budman111

Well-Known Member
rkymtnman said:
luckily i caught it after just 2 days. a full dose of cal/mg stopped it in its' tracks.

so you think a good solution is to just add cal/mg after the stretch is over? any idea of what ppm value i should be targeting for total Ca?
Click to expand...
I have soft water so I supplement calmag without PPM checking but given at recommended dosage of 1ml/L has never reoccurred the issue so that's what I give with my base Canna Flores @ 1/2 strength
 
Randomblame

Randomblame

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.
Click to expand...
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.
VPD Chart -1°C Leaf Temps.gif
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.
 
3rd Monkey

3rd Monkey

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.
Click to expand...
That actually makes a lot of sense. A lot.

I didn't know anything about the temp and humidity, but I see it now with what I did.

I have a T5 in the tent to warm it up and my exhaust is in a timer, 1 hour on 3 hours off. My tent floats low 70s with fan on, low 80s with the fan off. Humidity is what's off. Fan off, I have around 50% humidity, fan on about 30%. Explains the water uptake.

Given what I've seen in this "experiment" I would have to say you are definitely right. Spot on actually. Blew my fucking mind lol.

Thank you very much. I will adjust and report back, problems or not.
 
xtsho

xtsho

Well-Known Member
Calmag is the most overused additive there is. Calmag issues go away if your nutrient uses calcium nitrate for the nitrogen source. Its more expensive than the other sources but it's much better. Provides both nitrogen and calcium. Nutrients that don't use it for their main nitrogen source typically also have their own brand of calmag. That's so they can make you pay again for something that should already be in their base nutrients. It's not LED related it's nutrient related.
 
3rd Monkey

3rd Monkey

Well-Known Member
xtsho said:
Calmag is the most overused additive there is. Calmag issues go away if your nutrient uses calcium nitrate for the nitrogen source. Its more expensive than the other sources but it's much better. Provides both nitrogen and calcium. Nutrients that don't use it for their main nitrogen source typically also have their own brand of calmag. That's so they can make you pay again for something that should already be in their base nutrients. It's not LED related it's nutrient related.
Click to expand...
If that's the case, why don't they do it under the HPS?
 
3rd Monkey

3rd Monkey

Well-Known Member
xtsho said:
There are tons of growers using LED's that don't have any issues with calcium or magnesium deficiencies.
Click to expand...
I believe you. There are probably just as many that do wind up with issues too.

Just saying that in my particular case, HPS can take full nutes and roll. LED can't. Could be my LED, or my HPS, I dunno but I've seen others with issues and I think that @Randomblame just knocked it out of the fucking park with that synopsis.
 
S

Special Kdog

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.
Click to expand...
What type of water are you using? The only time i've had issues is when the tent is too hot or I abuse the girls a whole lot for a scrog. I think my tap water has some of those nutrients as well as my soil. BTW i want to give a shout out to those HLG lights. I've had multiple types of LEDs for 8 years. still running a VIPAR but the girl under the HLG light well it is amazing. Your CalMag is gonna depend on your water, your soil, and IMO your heat. I use it a little before I switch to flower and run through about 4 weeks. My next fert i will use some but then i'm done. 6 more weeks to harvest.
 
3rd Monkey

3rd Monkey

Well-Known Member
Special Kdog said:
What type of water are you using? The only time i've had issues is when the tent is too hot or I abuse the girls a whole lot for a scrog. I think my tap water has some of those nutrients as well as my soil. BTW i want to give a shout out to those HLG lights. I've had multiple types of LEDs for 8 years. still running a VIPAR but the girl under the HLG light well it is amazing. Your CalMag is gonna depend on your water, your soil, and IMO your heat. I use it a little before I switch to flower and run through about 4 weeks. My next fert i will use some but then i'm done. 6 more weeks to harvest.
Click to expand...
Well water filtered to 20-30ppm. My compost has calcium in it, that's what threw me, but I saw the K tox first, but now I know why.
 
You must log in or register to reply here.
Top