Grow Mediums What happens to the K and Na after buffering coco-coir?

[elcoloan]

Tittle pretty much says it all. I wonder what happens with those elements that are replaced with Ca and Mg.

Do the K and Na stay in the medium? Or do they go away in the runoff water? If they stay, are they absorbible by the plant? Any recommended reading that could solve these questions?

Context: These questions all stem from my current plant (https://www.autoflower.org/threads/...b-coco-hempy-bucket.72131/page-3#post-2165680) showing what i consider a slight N def in some lower leaves while being dark green all around. I can't increase the base nutes nor the calmag dosage because I get yellow tips. So i was thinking maybe it's not due to lack of N, but antagonism due to too much K in the medium? I use Mega Crop v1 which also has high K, and this cococoir i'm using right now was not properly buffered.

 

[Arthur]

What's left in the medium really depends on how much your running thru, too runoff? Or well past? Do you preventative flush? Watch ph and ppm of feeds and medium?

I'm guessing its P. beginning Phosphorus deficiency can show as a deep green.

It is my arch enemy... a beautiful deep green... that begins having more and more issues as flowering builds. If your behind by the time it presents fully in flower, your in a chasing game.

 

[Arthur]

High medium ppm would indicate a salt buildup. In that case a good flush is the solution.

 

[elcoloan]

@Arthur ... I check input and runoff ppms of every watering/fertigation, and always try to get 20% or more of runoff. Input is 300-350 ppm (0.5 conv), while runoff is 20-40 ppm. I don't check runoff pH, but always set input between 5.8-6.2, mostly 6.0-6.2 .

 

[Arthur]

I've never been big on runoff tests, but I do pH and ppm the medium itself a couple times a grow, especially if I see issues.


Do just prior to feeding.
1 part medium from your pot. I use a shot glass and try and get about level.
Equal part water you use. Let set about 5 minutes and carefully check pH and ppm.

This will give you an accurate look where the plant is feeding. Under 200 increase feed. over about 600 and your getting too hot. More than that it's time to flush and reset.

Careful with the pH pen and the mix, bulb is glass, and a piece of hard perlite can ruin your day...

 

[Shiva's Mistress]

Tittle pretty much says it all. I wonder what happens with those elements that are replaced with Ca and Mg.

Do the K and Na stay in the medium? Or do they go away in the runoff water? If they stay, are they absorbible by the plant? Any recommended reading that could solve these questions?

Context: These questions all stem from my current plant (https://www.autoflower.org/threads/...b-coco-hempy-bucket.72131/page-3#post-2165680) showing what i consider a slight N def in some lower leaves while being dark green all around. I can't increase the base nutes nor the calmag dosage because I get yellow tips. So i was thinking maybe it's not due to lack of N, but antagonism due to too much K in the medium? I use Mega Crop v1 which also has high K, and this cococoir i'm using right now was not properly buffered.

After you buffer, do another heavy rinse with pure water.
The Na and K in particular, which are in the unbuffered coco, will just dissolve into the water and flush out.
That's the theory, anyway. Though some amount of Na and K will remain bound to the cation sites.
The plants do need some amount of K, hence the NPK fertilizer.
Though usually coco-specific fertilizers have less K, because there's already more in the coco.
Probably needs some tiny amount of Na as well, but unwashed / unbuffered coco has far, far too much.
Having too much residual K and / or Na will also affect the pH, which may be one of your problems.
If Mega Crop has high K to begin with, prob not so good.

So you didn't do a wash / rinse and then a buffer in the first place on your coco, right?
It's not too hard to do.

First, wash, wash wash that coco. I like to use a cloth pot, because I can just flush tons of water through it.
The water run off starts dark brown, like tea, and slowly goes clear.
Other people recommend using a sieve, to get out smaller particles that a cloth pot won't get.
True, and would be best. I just don't have a big sieve.

Then mix up a big bucket of high Ca / Mg solution, maybe 300-500 ppm worth or so.
If you have straight Ca / Mg, that's great. I don't. I use a high Ca / Mg part B of a hydro fertilizer, Peters.*
Drop my cloth pot with washed coco into the bucket.
I let is sit overnight. Some say just an hour or so is okay, but recommend buffering twice.
I just do it once, but for longer. Agitate the solution every now and then, to make sure it gets into the coco.

Then heavy rinse again. The water starts brown again, because it's got the Ca / Mg solution color.
But again it ends up clear, and my ppm reading is something like 50, which is just like my water.
* Even though I don't use Ca/Mg only, and have other NPK in that solution, the flush at the end deals with it.

I've done it like this for quite a few grows now, with a couple of types of coco.
All my coco is cheap as dirt brick compacted type, because that's all I can get here (without importing...)
I don't grow in straight coco, I mix with potting soil and some organic amendments.
Sometimes my coco is over 50% of the mix, though.
And I haven't had any problems, pH lock out, freaking high K or Na, high ppm run off levels, etc.

 

[elcoloan]

...
First, wash, wash wash that coco. I like to use a cloth pot, because I can just flush tons of water through it.
The water run off starts dark brown, like tea, and slowly goes clear.
Other people recommend using a sieve, to get out smaller particles that a cloth pot won't get.
True, and would be best. I just don't have a big sieve.

Then mix up a big bucket of high Ca / Mg solution, maybe 300-500 ppm worth or so.
If you have straight Ca / Mg, that's great. I don't. I use a high Ca / Mg part B of a hydro fertilizer, Peters.*
Drop my cloth pot with washed coco into the bucket.
I let is sit overnight. Some say just an hour or so is okay, but recommend buffering twice.
I just do it once, but for longer. Agitate the solution every now and then, to make sure it gets into the coco.

Then heavy rinse again. The water starts brown again, because it's got the Ca / Mg solution color.
But again it ends up clear, and my ppm reading is something like 50, which is just like my water.
* Even though I don't use Ca/Mg only, and have other NPK in that solution, the flush at the end deals with it.
...

Thanks! It's pretty much what I do now It works quite well. I use a strainer though and not so easy.. will get my self a cloth pot as well.

 

[Olderfart]

I throw my dirt cheap coco in a plastic tote, add lots of water, enough to swim the stuff totally, give it a serious stir for a while, then strain it. This gets rid of lots of fines. Then I do the same thing again with a double concentration of cal mag, only leave it soaking overnight before straining it again. Finally, I do a serious rinse with my ph'ed nute mix for seedlings, sieve it, and it's ready for adding ~40% perlite after being left to drain well. Once drained and perlited, it is ready to plant seedlings in, already charged with seedling nutes.

Works a treat, the cheap bricks are available locally, and I know exactly what is in the stuff when I plant my seedlings.

 

[Shiva's Mistress]

Thanks! It's pretty much what I do now It works quite well. I use a strainer though and not so easy.. will get my self a cloth pot as well.

Yeah, give the cloth pot a try.
I used to use big plastic soil bags, and stab holes with a knife.
Works, but ... cloth pot is easier.
Doesn't get a lot of the small fibers, but seems okay to me.

I throw my dirt cheap coco in a plastic tote, add lots of water, enough to swim the stuff totally, give it a serious stir for a while, then strain it. This gets rid of lots of fines. Then I do the same thing again with a double concentration of cal mag, only leave it soaking overnight before straining it again. Finally, I do a serious rinse with my ph'ed nute mix for seedlings, sieve it, and it's ready for adding ~40% perlite after being left to drain well. Once drained and perlited, it is ready to plant seedlings in, already charged with seedling nutes.

Works a treat, the cheap bricks are available locally, and I know exactly what is in the stuff when I plant my seedlings.

Yeah, really soak it, lots of water is the way.
You do an overnight Cal Mag soak too!!!

I don't pre-charge because I use my coco organic.
(Yeah, okay, my buffer isn't organic, I know, I know... )
Though I did do that for my first coco grow, using Advanced Nutrients.

Hope others can learn from your posts.
Saw a YouTube vid the other day, quite well known Autoflower grower,
he tried coco for a grow, and totally fncked it up,
because he neither rinsed nor buffered.
His plants looked like sh!t, poor guy...

 

[Mizzo81]

Get some @Rain Science bags. They work even better then cloth because they will let more of the fine dust through the cloth won’t. Makes for better drainage and aeration.