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Potassium def, or...???

ButterflyEffect

Well-known member
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It sure looks like K def, to me. Plants are stacking well, otherwise.

Here's the feed situation.

Jacks 3/2 with 1/2g/G MKP and 60ppm of Biomin Calcium. There's also 1ml/G of Mr Fulvic. Very strong stuff, as it seems. EC is about 1.6

I can't recall my ratio before today since I just made changes to the recipes again this morning. My current ratio is 163-71-211-182

Mixed strains in the room, the issues are mostly on the 2 Black Zombies. Plants are in hempys, fed daily. The room is vertical with stacked 315 CMHs.

I doubled the MKP to 1g/G to see you that works out, but other than not getting worse, how would I tell if it was the right course of action? I don't want to overdo it with the MKP especially.

I had a few ideas...

I starting ramping up Ca 2 weeks prior to flip and through transition and their stacking like they never had prior in the 5 years I've been growing. Did the extra stacking make demands for K?

Or..

Maybe the Mr Fulvic is chelating so well that the plants are getting to much of something?

Or...

Maybe I still need more Ca and it's not allowing enough K?

Still learning!
 

dramamine

Well-known member
Not sure what medium you're in, but in my experience (in coco), when you push that much calcium, you may see deficiencies of K. Cation exchange sites are occupied primarily by Ca and K, so too much of one preempts the other.

Short version: high Ca is great, but K needs to be high in proportion. This can mean running a higher EC feed is necessary.
 

AgentPothead

Just this guy, ya know?
:yeahthats Applying too much calcium and magnesium can cause a potassium deficiency; the K/Ca and K/Mg ratio should always be kept above 2 (but below 10, since too much K can hinder the absorption of calcium and magnesium). Too much potassium can also prevent the absorption of certain micro-elements, such as zinc. It is particularly important to take account of this interaction when using very hard water with a high calcium and magnesium content.
https://www.cannagardening.com/interactions_between_nutrients That's the Canna nutrients website, it can definitely be an issue if you are in coco.
 

ButterflyEffect

Well-known member
Not sure what medium you're in, but in my experience (in coco), when you push that much calcium, you may see deficiencies of K. Cation exchange sites are occupied primarily by Ca and K, so too much of one preempts the other.

Short version: high Ca is great, but K needs to be high in proportion. This can mean running a higher EC feed is necessary.

Ok. That makes sense. I read about that potentially being an issue.

My hempys are 4:1 perlite and vermiculite. Fed full strength to runoff daily. If they can't make it 24 hours, I hit them with water only and I time it so that happens toward the end of their light cycle.

I just changed the recipes on my spreadsheet this morning so I can't recall exactly what I was giving them. My K:Ca ratio is 211:182 now but I assure you that the K was a good bit higher before todays change. The Ca would've been higher but not proportionally.

Thanks for your input. It's very much appreciated.
 

ButterflyEffect

Well-known member
:yeahthats Applying too much calcium and magnesium can cause a potassium deficiency; the K/Ca and K/Mg ratio should always be kept above 2 (but below 10, since too much K can hinder the absorption of calcium and magnesium). Too much potassium can also prevent the absorption of certain micro-elements, such as zinc. It is particularly important to take account of this interaction when using very hard water with a high calcium and magnesium content.
https://www.cannagardening.com/interactions_between_nutrients That's the Canna nutrients website, it can definitely be an issue if you are in coco.

Thanks for helping with the understanding. That's what's been driving me crazy! I had also been doing foliars of Growmore Calmag so in addition to the added Biomin, my Ca numbers must be through the roof!

The irony that I was deficient in calcium and went full throttle in the opposite direction doesn't escape me.

Living to learn another day!
 

AgentPothead

Just this guy, ya know?
Glad to help bro, everything is a learning experience, especially growing weed. I like being able to help people with problems cause the next time I see that problem should be able to diagnose easier.
tiphat.gif
If I can remember it that is :D
 

ButterflyEffect

Well-known member
Glad to help bro, everything is a learning experience, especially growing weed. I like being able to help people with problems cause the next time I see that problem should be able to diagnose easier. View Image If I can remember it that is :D

I hear ya! I need to start growing the kind of bud that makes me forget so I don't have to blame it on old age!
 

f-e

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Mentor
Veteran
:yeahthats Applying too much calcium and magnesium can cause a potassium deficiency; the K/Ca and K/Mg ratio should always be kept above 2 (but below 10, since too much K can hinder the absorption of calcium and magnesium).


With the advent of LED lighting, I'm not sure how applicable this age old wisdom still is. My numbers are very much like the OP's with 215K and 165Ca. In the first week of bloom Ca is lacking, then around 10 days the balance seems alright. Though I have been using more K experimentally in answer to the pH of my runoff showing it got used. In the last week of bloom they can scream for Ca with these levels. I'm about to pull back on the Mg in order to get it ahead. As I'm 2:1 and feel 3:1 is worth trying

Perhaps the OP could measure their run-off pH to discover if it's dropping to around 5 due to the K being used. A pH where K availability is very low, even if you have some.

I'm literally playing about with this now. Moving to N-acid in the hope they will eat my pH down along with the K and help the pH not fall so far. At day 8 I saw 4.8 running off and with additional K it's now 5.4 but I'm still not happy. The Nacid is in the tank but they have not been fed it yet.

The P is low isn't it? Most PK boosts are not that far apart and my base feed isn't either. P is like a carrier and energy component. Mine is down there in grow but much higher in bloom. As an example, my base grow feed puts P around a third of N but the bloom puts it higher than N. That's Ionic not something I made myself.


Edit: I'm just a voice on the internet trying to find my own way. Nothing I say is from a book. I don't give expert advice. It's guesswork and trial.
 

ButterflyEffect

Well-known member
With the advent of LED lighting, I'm not sure how applicable this age old wisdom still is. My numbers are very much like the OP's with 215K and 165Ca. In the first week of bloom Ca is lacking, then around 10 days the balance seems alright. Though I have been using more K experimentally in answer to the pH of my runoff showing it got used. In the last week of bloom they can scream for Ca with these levels. I'm about to pull back on the Mg in order to get it ahead. As I'm 2:1 and feel 3:1 is worth trying

Perhaps the OP could measure their run-off pH to discover if it's dropping to around 5 due to the K being used. A pH where K availability is very low, even if you have some.

I'm literally playing about with this now. Moving to N-acid in the hope they will eat my pH down along with the K and help the pH not fall so far. At day 8 I saw 4.8 running off and with additional K it's now 5.4 but I'm still not happy. The Nacid is in the tank but they have not been fed it yet.

The P is low isn't it? Most PK boosts are not that far apart and my base feed isn't either. P is like a carrier and energy component. Mine is down there in grow but much higher in bloom. As an example, my base grow feed puts P around a third of N but the bloom puts it higher than N. That's Ionic not something I made myself.


Edit: I'm just a voice on the internet trying to find my own way. Nothing I say is from a book. I don't give expert advice. It's guesswork and trial.

I'll check that runoff tonight when the room is on. That's an interesting point that I wasn't aware of.

Since I'm constantly tweaking things, I changed my ratios yet again.

Now wks 4-6 are at 1.3EC -- 156-54-189-139-51 -- 3:1:3.5

That comprises 380ppm of Jacks, 255ppm of Calnit and 27ppm of MKP.

I think the biggest challenge is determining what ratios to run and when. You hear so many differing opinions and I know some of it is media dependant, but the rest seems like guesswork.

At some point I'l have to pony up for tissue analysis.
 

f-e

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1.5:1.4:3.1 (% not ratio) Ionic coco Bloom.
2:2:4 (%) Canna Terra Bloom

Listening to internet opinions, gets you people like me who think their bloom has more P than N :) Though as you see these two big players are using a lot more P than you.

Ionic coco grow 1.9:0.7:2.6 (%)

I spend a week on grow, boosting the P to ~1.5%. Like some others, I watch for the pH drop in my runoff that indicates bloom is needed. This is about a week with LEDs but maybe 2 weeks with HIDs. This seems to be where LED's pull ahead for me. Seen in the plants development and food requirement. Years ago I didn't know why I watched the pH I just saw it somewhere and found it little use. Only the last year have I pinned to down to the K through observation. So just maybe I'm wrong. Though I very much doubt it.
 

f-e

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Oh.. It's my thinking that eating a certain amount of K will cause a certain shift. So all that can be gauged is that it's getting taken. We can't see from the pH if it was enough. I just want to know, that whatever they took, didn't take the pH so low that they literally cut themselves off from getting more.

I can't quite be right, as giving more K has stopped the downward drift going so far down. My real goal is keeping in in range though. That is what you should be looking at. Though I must stress I do walk my own path. Perhaps others might chime in here. It's a round table.
 

ButterflyEffect

Well-known member
Oh.. It's my thinking that eating a certain amount of K will cause a certain shift. So all that can be gauged is that it's getting taken. We can't see from the pH if it was enough. I just want to know, that whatever they took, didn't take the pH so low that they literally cut themselves off from getting more.

I can't quite be right, as giving more K has stopped the downward drift going so far down. My real goal is keeping in in range though. That is what you should be looking at. Though I must stress I do walk my own path. Perhaps others might chime in here. It's a round table.

You're in coco, correct? I wish I could get past the learning curve with coco. Plus I've heard that there are batch consistency issues. On the other hand, I could go back to tanks for each room with Blumats again! Instead, I get to mix several 5G buckets daily and hand water.

I forgot to check runoff tonight, but I moved it to my to-do list for tomorrow. I'll check back with what I get, but I've already made recipe adjustments so I'm not sure what I'll tell me at this point. Definitely going to keep that in mind, as I almost never check runoff.

Thanks for the input. It's why I love this place.
 

ButterflyEffect

Well-known member
Oh.. It's my thinking that eating a certain amount of K will cause a certain shift. So all that can be gauged is that it's getting taken. We can't see from the pH if it was enough. I just want to know, that whatever they took, didn't take the pH so low that they literally cut themselves off from getting more.

I can't quite be right, as giving more K has stopped the downward drift going so far down. My real goal is keeping in in range though. That is what you should be looking at. Though I must stress I do walk my own path. Perhaps others might chime in here. It's a round table.

I checked the pH of two of my rooms today. The room in question(Day 40) was pH in =5.8; pH out = 6.4. The other room(Day 4) pH in = 5.8; pH out = 7.1

Not sure what to make of that yet, but at least it's not really low.
 

f-e

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Okay. So not eating all the K. It may even to too high.
What's the EC coming out? I'm not sure why I didn't ask before.

My Nacid experiment was a flop. The run-off was no different to the pH seen using P-acid.

It's very strange. I can see all-sorts going on. The only thing not hinted at at all is Mg but maybe I'm just not looking hard enough. This would tie in with toxicity from a low run-off volume, letting the EC in the substrate climb.

Most of the time I'm called to a coco problem I test the run-off ec and find it's off the clock. Why I didn't ask, I don't know.
 

ButterflyEffect

Well-known member
Okay. So not eating all the K. It may even to too high.
What's the EC coming out? I'm not sure why I didn't ask before.

My Nacid experiment was a flop. The run-off was no different to the pH seen using P-acid.

It's very strange. I can see all-sorts going on. The only thing not hinted at at all is Mg but maybe I'm just not looking hard enough. This would tie in with toxicity from a low run-off volume, letting the EC in the substrate climb.

Most of the time I'm called to a coco problem I test the run-off ec and find it's off the clock. Why I didn't ask, I don't know.

You know, I didn't even check EC. I'll check the first room in a few minutes and the other one later. Now I'm in hempys, so there's obviously going to be runoff. The feed doesn't really have any dwell time in the substrate before it hits the res and then the weep hole. I wonder if that has an effect on the experiment?

Maybe too much Mg? I know folks like Slow Nickel and Jidoka have said that people use way too much Mg, at least in the rootzone.
 

f-e

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Interesting. My efforts to increase Ca have been hampered by the Mg content of the calmag product I was using. I'm quite sure of it. I have picked up some Canna Mono now and will use a little epsom as I like the idea it comes with sulpher. Which aids the smell. Small steps though. I'm just throttling back on the Mg for now.

Mg is very soluble so isn't where I would first look for accumulation. I tend to water to 'just' reaching runoff. Pause. Then give the extra 30% or so. This increases the ec a lot, as it gives the salts a while to dissolve.

I record pump run times and run-off volume, knowing my drip rates. Along with ec and ph in/out and just what I mixed. I know some just runs though, it's not really my root zone I'm measuring. But it is good comparative data. So you can watch trends over time. Without all that, you still might just find a crazy number.

I also feed about 1.6 typically. Aiming for enough run-off to keep below 2.0 as this figure has a direct impact on when I first see brown hairs and their speed of progression. Not in a good way either. If I'm seeing numbers like 2.4-2.6 I can have them browned off in 35 days. The K seems to be the biggest influence over just how bad exactly.
 

ButterflyEffect

Well-known member
Interesting. My efforts to increase Ca have been hampered by the Mg content of the calmag product I was using. I'm quite sure of it. I have picked up some Canna Mono now and will use a little epsom as I like the idea it comes with sulpher. Which aids the smell. Small steps though. I'm just throttling back on the Mg for now.

Mg is very soluble so isn't where I would first look for accumulation. I tend to water to 'just' reaching runoff. Pause. Then give the extra 30% or so. This increases the ec a lot, as it gives the salts a while to dissolve.

I record pump run times and run-off volume, knowing my drip rates. Along with ec and ph in/out and just what I mixed. I know some just runs though, it's not really my root zone I'm measuring. But it is good comparative data. So you can watch trends over time. Without all that, you still might just find a crazy number.

I also feed about 1.6 typically. Aiming for enough run-off to keep below 2.0 as this figure has a direct impact on when I first see brown hairs and their speed of progression. Not in a good way either. If I'm seeing numbers like 2.4-2.6 I can have them browned off in 35 days. The K seems to be the biggest influence over just how bad exactly.

Did that runoff in room 1 and veg this am.

Flower 1 = pH in 5.8; Out 7.0 -- ppm in 725; Out 1030
Veg = pH in 4.6; Out 7.2 -- ppm in 655; Out 1060

I just don't know how to decipher this. In veg, I was having an issue that really looked like high pH. The Biomin was spiking it to like 8! For some reason, my veg mix came in pretty low, not sure why. My flower ones come out at 5.6 mostly. Maybe the Epsom? Anyway, it still came out at 7.2 in runoff! Confused. Even the other rooms are, as well. Maybe I keep mixing to 5 or lower and watching it until it comes down to at least 6. We'll see.

Can you get the Growmore calmag? Bill Farthing recommended it. It's a 2:1 Ca/Mg. Although no MagSul, though. Everything is either a citrate, acetate, carbonate or glucoheptonate, No N, which is nice.

Next up, gypsum experiments! Yay!
 

f-e

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That is a large gap between in&out. Something is present in large quantities. Eating P&K lowers pH so I guess not a lot of that is going on. While N use raises pH.

I have had to lower my K use and increase my N use throughout flower since going LED. I saw run-off figures like yours until I did this. My fix as first was simply more runoff until I figured the K was the big issue. The P and N info comes from online but I have seen evidence of N use raising pH. Except urea which lowered it, but for other reason than H ion exchange and the same reasons stop people using it. I can't substantiate the P claim, it's just another voice on the internet.

IIRC hydro food does have a lot more K than needed nutritionally. It's abundant to solve a math problem. It's many years since that topic was a hot one so I don't quite remember. I'm very wary of K right now though. Even with your plants asking for it, I would be sorting out that high run-off first.

Just take one plants and put a crazy amount through. Enough to get the runoff within 20% of what went in. Then see how the plant responds.
 

slownickel

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When you apply a lot of Calcium, you have the responsibility to apply much more K than you are used to. With that said, sure likes you have a Ca deficiency too!
 

ButterflyEffect

Well-known member
That is a large gap between in&out. Something is present in large quantities. Eating P&K lowers pH so I guess not a lot of that is going on. While N use raises pH.

I have had to lower my K use and increase my N use throughout flower since going LED. I saw run-off figures like yours until I did this. My fix as first was simply more runoff until I figured the K was the big issue. The P and N info comes from online but I have seen evidence of N use raising pH. Except urea which lowered it, but for other reason than H ion exchange and the same reasons stop people using it. I can't substantiate the P claim, it's just another voice on the internet.

IIRC hydro food does have a lot more K than needed nutritionally. It's abundant to solve a math problem. It's many years since that topic was a hot one so I don't quite remember. I'm very wary of K right now though. Even with your plants asking for it, I would be sorting out that high run-off first.

Just take one plants and put a crazy amount through. Enough to get the runoff within 20% of what went in. Then see how the plant responds.

Indeed baffles the mind.

I've been trying to study up on how all of the elements interact while keeping it in context to the substrate, lighting and VPD.

Plants seem mostly ok, but not perfect. The veg plants are much better and I think I have them in check. Still runs off at 7.0. PPM isn't much higher than the input, which is nice.

I already ran 3pH water through veg and one flower room. No difference. Still 7.0.
 

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