MKP PK Mixing

[f-e]

Readings Bill's in depth thread about cheap nutrient lines, got me interested in MKP. Also known as Monopotassium Phosphate amongst other names.
As a powder, it's 0 - 52 - 34 (oxides, like typical labeling)
I mixed it at 100g per 650ml of water.
This made a 0 - 3 - 3.7 elemental solution. Something like 0 - 7 - 4.6 as oxides
I could only mix it this strong. About 20% more and it wouldn't dissolve at 20c. I wouldn't put this in the fridge, as some salt would come out of solution.
It was easily available online, in any quantity.

Most boosters are heavier on the K than P. They are aimed for a little later in bloom. P is something you load up with early. It helps build strong roots and frames, adding branching, then size to the buds, that K fills in.
Many bottled feeds think 30-40ppm P is ample. While 100ppm is actually average, and often targeted specifically. This solution, used 1ml per liter, will offer a 30ppm bump.

The range of P numbers seen commercially, is really quite vast. I have included an image demonstrating this.



If anyone would like to check my mixing figures, a little confirmation would be nice. Before anyone gets chance to start mixing their own.

Thanks BillFarthing

 

[f-e]

I use this because adding calmag to my base feed, adds nitrogen. What I'm doing, is using less of my base feed, to get the N back down. This leaves me low on P and K which this corrects. Taking my K back up where it should be, but increasing P above the bases idea of what's enough. This is for the first two weeks of bloom, while they get their frames set up and stack some bud sites. Once past two weeks, I'm using PK as that's more like the ratio's of PK in the base. I no longer wish to load up with P, and it's time to edge the K ahead for flower production.

It's a move from P bias to K bias that not everyone agrees with.

 

[BillFarthing]

I run my Phosphorus 40-60 ppm start to finish. The plant needs just sufficient P. Adding extra doesn't force feed the plants. You are right on that early P is better than late P.

Potassium late flower really boosts yield and TAC. MKP is an economical way to get it done, but I suggest Homemade Hammerhead, which has a better ratio between the two.

 

[f-e]

Hey Bill. Thanks for passing by.
I need to iron out my K boost still. I'm also looking at potassium sulphate as 'sulphate of potash' is what they offer in our garden stores here. I think you yourself mix MKP and SOP together dry, and drop a gram in a gallon of nutrient solution iirc. I'm not sure if I can mix them wet. I have canna mono K at the moment, which offers some flexibility I like. The last week or so I don't raise P much above 20ppm, but the K is going in upwards of 150 before flush.
SOP is about 50% K or little over 40% elemental. I might water it down to 4% in line with the MKP. As you know, a typical 13/14 or 14/15 bottle is 6/12 elemental, so having a 3/3.7 and a 0/4 is a fair bottle combination to play with. If it dissolves.

 

[jackspratt61]

Hey fe

Have you worked out your problems from a few months back?

 

[f-e]

Hey fe

Have you worked out your problems from a few months back?

Some.. but I'm nowhere near where I should be.
Here I am posting a P additive, while my current trail is reduced P. Nothing to report really. I will update when I have something conclusive. Less food though, except the K. N can be 40ppm after stretch before I see any deficiency. I seem to have a handle on the interveinal clorosis in the upper shades, using Ca levels that are fairly high beside other inputs. After stretch, I'm averaging 42-45-120-90-30 but still the hairs turn brown at day 23 like clockwork. 5% by day 26. By day 35 they can look half done. I took up K to 180 for the second half of bloom last run, with P down at 20 and they seemed to stop browning and get back to fattening up. 25% higher yield, but had 15% longer so inconclusive. I let it slip to save trimming Christmas/new year. Run-off sampling before was showing a fair bit of P coming out. I also know PK browns hairs the same way (from the base, starting with a red tinge, then brown) and high K low P seemed to look alright. Other stories I read speak of P excess leading to red colouring in various parts. I'm not sure how true that is, as red is more commonly deficiency (or stress) but some weight falls behind the idea it's P causing me problems. I have not pulled up down from 45ppm at 14 days though as I might of liked. Its 30ppm as the hairs started to turn. too early to say if they are turning slower, but perhaps the slow down in budding isn't so obvious. I'm certainly not getting the thin spear like buds. No coke cans though. Which I could do with about 45ppm before everything went wrong. So I kinda know I should be barking up the wrong tree with this, but they browned early and flat topped, even though they produced.
As I say, nothing conclusive. Covering old ground, as there is no new ground I can see. Which is why I put up that thread. Which seems 10 grows ago now

I may have to do some big tubs of organic soil, just so I can't have any part in things

 

[jackspratt61]

Some.. but I'm nowhere near where I should be.
Here I am posting a P additive, while my current trail is reduced P. Nothing to report really. I will update when I have something conclusive. Less food though, except the K. N can be 40ppm after stretch before I see any deficiency. I seem to have a handle on the interveinal clorosis in the upper shades, using Ca levels that are fairly high beside other inputs. After stretch, I'm averaging 42-45-120-90-30 but still the hairs turn brown at day 23 like clockwork. 5% by day 26. By day 35 they can look half done. I took up K to 180 for the second half of bloom last run, with P down at 20 and they seemed to stop browning and get back to fattening up. 25% higher yield, but had 15% longer so inconclusive. I let it slip to save trimming Christmas/new year. Run-off sampling before was showing a fair bit of P coming out. I also know PK browns hairs the same way (from the base, starting with a red tinge, then brown) and high K low P seemed to look alright. Other stories I read speak of P excess leading to red colouring in various parts. I'm not sure how true that is, as red is more commonly deficiency (or stress) but some weight falls behind the idea it's P causing me problems. I have not pulled up down from 45ppm at 14 days though as I might of liked. Its 30ppm as the hairs started to turn. too early to say if they are turning slower, but perhaps the slow down in budding isn't so obvious. I'm certainly not getting the thin spear like buds. No coke cans though. Which I could do with about 45ppm before everything went wrong. So I kinda know I should be barking up the wrong tree with this, but they browned early and flat topped, even though they produced.
As I say, nothing conclusive. Covering old ground, as there is no new ground I can see. Which is why I put up that thread. Which seems 10 grows ago now

I may have to do some big tubs of organic soil, just so I can't have any part in things

Are you still in used coco and under led?
RO water?

 

[f-e]

I have switched to RO since, but it's not really changed anything. I'm on about the forth soil run. So different feeds. Did one different in coco first. Same LEDs which I kinda question, but it seems so unlikely. Lower feed strength seem the biggest improvement. However I'm just at 600umol, not 900+ like I started out with before my issue crept in. Timeline goes from a few at 22 per meter, then a gradual decrease to 12 where to flatlined through feed and substrate changes. Only on the last run did I see an increase to 16 but they had 15% longer. It was at the end things happened though. Not just the extra time, but leading up to it. After lowering the P in my mix a lot, and pushing the K up a little. Though not not past levels. I actually dropped the P from 42ppm to 14ppm and moved the K from about 125 to near 170. That is a wide gap, but P accumulation within the plant was taken care of I think. Perhaps by the end of stretch looking at some peoples research. While K at the end is weight. They seems to push again, producing more white hairs, but not the second spurt of excess, it was hairs within the original fattening buds. Which is the most promising thing I have seen. Commercial surveys still saw the average P used was about 100ppm last year (40% surveyed were outdoor) but the scientists are still formulating things around 30ppm.

I need to look at P movement next, as a lot of the damage is overnight. When feed moves differently within the plant.
I have the underlying nagging voice telling me it used to be alright though. I have bought in a few new things and they perform no differently. I have hand watered a cycle with new things, to ensure little cross contamination. Thinking virus.
I need to change my lights next. It's not drastic, as I use QB's for this very reason. A board is about £30 ($40)

 

[jackspratt61]

I switched from hps to led. And from coco to 100% perlite. No influence from organic matter and a cec of 1.5. Big difference in feeds between substrates.
Perlite mix at full illumination from growers choice 680s likes feed at 120-70-185-150-65-196 *high sulfur from using gypsum as calcium source.
Have to water less each session with higher ec.

 

[f-e]

They are the kind of numbers I expected to settle with. About where I started before things went wrong actually. I find no real logic behind what I'm doing now, but I'm straying from the course as it decided not to work anymore. Which is a crazy thing to happen. Impossible you might say. However, what worked, now doesn't.
I have a couple of other projects that stop me giving this the devotion it needs. One issue that really messes up my logs is that my ec truncheon drifted off. I think long before any of this, as I was finding the need to use almost 50% more feed for the same ec. I was down to 12oz before using another, making all my past ec readings little use. Though I do calculate PPM from bottles, and use ppm more than ec. I didn't do so until things went bad.

Perhaps it's the lights. Maybe the reds diminished and the blue got too far ahead. They don't look an odd colour though. Also, they are cold. I'm at 50% to make 600ppfd.

Reducing the air flow within the plants may of proved useful. Not really an RH change, but the stomata will presumably stay more puffed up. I was increasing airflow in responce to things were getting worse, but last run I left them off for weeks.

I have noted recently that the leaves doing that stuff up the sides are about gone. They tend to exist right at the air inlet, or just above the floor mounted 15w leds, where it's warm. Thus, the link would be environmental. They always were in clusters of better airflow. So some sort of toxicity seems likely. Last run I saw just two. Nothing to be overly concerned about, but still a guiding light. Moisture loss related, but not heat or RH driven.

 

[jackspratt61]

Something like 42-35-140-140-35 may be better for finish.
42-24-64-53-22 in veg.
Move the Ca up and down to keep the plant mostly root dominant.
Are you making your own micronutrient mix?

 

[f-e]

jackspratt61
I'm in canna terra at the moment. Peat based stuff that should be fed continuously. I have used Plagron 100% terra, which was a recommendation as I ran in the door with about 20 minutes till closing (barely time for tea). They only list NPK, but there is a range of other things present. Not calcium though. I'm using Canna Mono calcium, that leaves my hands lubed up. I think it must be calcium chloride so I can't put too much in. I forget the realistic limit though. I only just learned it's my only Ca source, so need to check.

While I have no problem with using Plagron, I'm flying blind without the numbers on the bottle. I just grabbed a bit to try, thinking I might get the other numbers somewhere. I need to switch. I want to try jacks, which is MB over here. However the small box weights have been out of stock forever it seems.


I'm way behind you with crop steering. I have not even seen an article of any worth. Though I know I must learn more than just steering to flower. You say changing Ca levels in any direction will lead to a root adjustment? I can use that.. My roots tend to loose the nice white colour after mid flower. I have not found the date yet. I'm watching closely this run. There is already some degradation at 4 weeks. White, but no real effort to keep producing fresh ones. I imagine there could be a strong link between browning hairs and the roots, promoted by some toxicity, or just maybe something missing

 

[jackspratt61]

what's the listed n-p-k

 

[f-e]

Headline figure is 2 2 4 but 2.1 - 1.6 - 3.9 on the back.

I use 2ml per L to get 42 - 14 - 64 as my base.

0.5ml per L of my mkp takes it to 42 - 29 - 80

Then 0.2ml per L of Canna Mono K (13.5% elemental) makes it 42 - 29 - 107

With some Potassium Silicate, it's closer to 120ppm K. That's about where I am mid bloom.

Mono Calcium is 8.8% and used 1ml per L after week 2. I used half this to finish on that last run, where I saw some increase.

Epsom for Mg


Needs a bit of fudging as I'm mixing by volume not weight. Obviously 1ml doesn't always weigh a gram.

 

[jackspratt61]

try your base only with calcium at 0.5ml/l
mg equal to p

 

[jackspratt61]

using led you have to raise ec

 

[f-e]

I was just hovering over the tank, thinking 0.5ml as I know that worked, towards the end. I didn't though. Today I didn't feed except ca and mg, as I want the P down, and know it hangs about. Sort of a flush day, but the runoff didn't change ec. It was my first big deviation from the plan. Now I'm at 42-14-110-88-30 as I can't really lower the Mg as they are asking for a little more. While dropping some lower leaves in the dark, that never bothers me, but I know more N would stop that. They mostly look Mg deficient though. I'm interested in minimums right now, so want to see everything show at some point. I think, for most of the bloom cycle, 40-15-120-50-30 just scrapes it for all of them. That's 3 times a day, having used about 70% of the full water holding capacity at that time, and getting 10-20% runoff.

 

[f-e]

using led you have to raise ec

When I first moved to LED I couldn't feed high enough. At theoretically toxic levels, they ate the lot before the next watering. The EC swing was huge. Over time it seemed to balance out. Then they started to want less. Much less. It seems some people have bumped ec 40% as I did and it worked. Others have been surprised how little was needed, which is where I have been led to. My nutrient use right now, is very close to that of sshz who's productivity is much like mine was before it all went pear shaped

Edit: I can feed normally, but at 2.5 weeks they stop eating. No matter what EC. Days later, the hairs start turning. If I ignore it and keep going, they just brown rapidly. Totally in 35 days. Barely drinking. Runoff EC too high to measure.
At this 2.5 weeks of similar EC in and out, the out starts to raise and the in must come down a third to keep the out in check. This slows the browning.
I'm thinking P as demand for it surely slows as the stretch finishes. That's the same 2.5 weeks. They stop stretching and turn to budding, and stop eating at the same time.
When I say feed normally, that's ec1.5 but in the beginning with LED that was 2.8 they were eating all of. Though my Ca and Mg were about where they are today.
I may of gone off the path a little, but thought this 40% more feed people did, might be more about Ca and Mg than anything else. Trials seem to support this.
I have tried going back to how I did things then, just to see if I had strayed way off path. It doesn't work anymore. That is itself really odd... Though since that rerun I have fixed other little faults that crept in. The big one being more oxygenation. After that last thread, I realised some black in my tank wasn't from the black feed and black additives I used. I had a bad tank, in terms of unwanted bio-life. Sucking the air out, I think. Steadily the coco had taken on a soil smell, and over a long time scale, so I hadn't picked up on it. My tank is awkward to access (under a ladder) so I had been lax, just chucking stuff in. Humic/fulvic/seaweed. Enough black stuff for me to get confused.

I have changed too much for it to be some outside toxification I can fix without moving. Only the tent remains, and some carpet. Gassing should slow, not come in the 4th cycle.
Lights? Really? Other people have them, but then most people would look at my grow and think it fine.

 

[jackspratt61]

Bringing the k too soon.

 

[jackspratt61]

k=ca 1 week before transition through till they begin to stretch. Then lower ca to get a good stretch. After stretch begin raising k while keeping equal ca. The feed is more about ratios than moving individual elements. Use base feed and ca/mg in correct ratios only. Bring more N if they need it.