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Everything EC related

Sockfilter

Sockfilter

New member
As I try to figure out more of the science around plant nutrition uptake, growing mediums, nute solutions etc, I realized that I post a few questions that may be more involved than what readers may want to know about (far from simple fix, but more of understanding plant sciences) as the resulting answer seems to always leave me with more questions.

So I started this thread for all of those that wish to know more, feel free to post any questions that are EC related and hopefully we can get some Plant guru's helping out (hint hint Campesino DANGERDAN ). Also could be a great place for heaps of consolidated EC info.

My question is in regards to EC inflow and outflow: (*everything below is in PPM)

"EC doesn't change because of interactions with the plant. EC can change due to interactions with the CEC of the media - but shouldn't in properly buffered Coco. Therefore, Evaporation is responsible for the changes to EC - and EC should always be higher in Run-off than Inflow. Run-off prevents it from becoming too much higher.
Finally, if the EC of run-off is lower than inflow in Coco - this indicates that the CEC is not buffered and the Coco is still stripping Ca and Mg from the nutrient solution." ~ Campesino

I have NO reservations about my coco not being fully/properly buffered (CEC of ca/mg replacing all the extras K's in the coir). Now my issues is exactly what Camp has stated, My EC inflow is 560, my outflow was 480's (yes lower and no Bueno from my understanding), last runoff was ~530's with a ~560 inflow.

Proper interval feedings in flower, fertigate @ lights on, ~6hr's later, 30mins prior to lights off. If I adjust my middle (middle of 12hr light cycle) feeding to a bit sooner, say 5 hrs, my runoff is always lower ~460, if I push it to 7hrs, my runoff is ~530 which is still lower than ~560 (inflow), yet we can see that transpiration (science) is working correct?

Now that I know that coco is unstable unless properly buffered, yet 4 weeks into flower, if everything looked good I would just maintain status quo however I took a double hit on N toxicity and Nute burn, hard recovery (around 15 day in flower) since the girl is full on flower production and no new leaves, I have her stable which I am good with, just trying to figure out a way to deal with the unstable coco and lower levels of EC runoff to maximize quality in a unstable grow medium while keeping nutrient lockouts at bay.

Thanks to all who wish to contribute, Happy Friday..:)
 
a while back i wrote a little post with a few charts called "ppm very important" with some info on EC scales and manufacturers. im not going to act like i know exactly how everything is/must be, but i feel you are overlooking other variables.

VPD is a relationship between temperature and humidity, and plays a mayor role in soil moisture evaporation and leaves respiration. all of this affects EC in different ways; high transpiration can cause the plant to drink lots of water but not necessarily lots of nutrients, rising the medium EC, or very low transpiration could make the plant drink less water but still taking nutrients from the soil.

this is just a little example, same variables with light; almost every strain will require more calmag under stronger lights (for example CFL vs HPS) variables like medium, nutrients, water hardness, rh, temp, vpd..etc, all drastically affect the numbers you get

all this assuming all strains are the same, witch is a very ignorant assumption from our part. we should all be more aware how different strains are and have different needs, like how sativas drink more water and indicas need more calmag...

i think you should consider many more thinks before reaching conclusions as simple as bueno or no bueno. you can learn as much as you want about that pheno you have on your setup/environment but most of it will only apply to the same pheno same setup... if you really want to know what is really happening inside the plant you going to need to read up on botany and wait for some educated members to really dig into your case. but without knowing temps and rh theyre all guild guesses (: i hope this helps sockfilter, i do not mean to discourage you but to open your perpective. in this site everyone tries to keep everything as simple as possible for new growers but sometimes creates confusions when people want to learn more and more.... just remember there are no recipies and no rules. only understanding what the plant is asking you for
 
9fingerleafs, agreed that there are heaps of other variables to consider Even within Phenos, however I feel that I am a very decent grower when just following the numbers on a package, yet when things get a little pear shaped, who the heck really knows right? As you said heaps of variables..:)

If I was looking for an exact solution to my exact problem I would have posted every variable that I log, however this is not the case as I am a confident grower, just looking beyond the basics to help evolve EC and it's uses for Dx'ing. Was thinking that general brainstorming ideas to help aid others in having the ability to self diagnose and think beyond the labels on products, YES that is a bit more info/learning that some are willing to take on and I respect that, however thought that some may find this area of topic intriguing and useful as I do..:)
 
Cheers Sockfilter I Love the Thread! Happy to Sub :)

I agree that this is not significant problem, more of a curiosity.
In my comment that you quoted, I made it seem that Buffering would be the only factor that causes EC of run-off to be lower, but that isn't true. If there are concerns about the buffer, then seeing these numbers would confirm a problem with the buffer. However, I too have seen lower run-off EC in plants I know are buffered. So I should have been more clear.
In my case, it turned out to be related to distribution of water during fertigation. I had installed my drip system with only two points of application per pot. I was getting run-off with small amounts applied and the coco far from the drippers was getting dry - And my EC numbers were crazy low. Right at inflow on most and below inflow on a couple. Despite this my plants started to get tip burn. When I hand watered with thorough distribution, run-off EC spiked up well above inflow.
I am not entirely sure about the chemical process that creates the situation, but if the water is not distributed well and there is horizontal wicking within the media, it seems to retain salts and almost filter the water as it passes through.
So if you are confident in the buffer, consider distribution - I can't remember your system/drippers. I would recommend doing a thorough hand-water and seeing if run-off EC is still low.

Happy to help brainstorm this, but again if the plant is healthy this is perhaps not indicative of a problem. It is certainly a better "problem" than uncontrollably high EC.

Curious to hear your response about distribution. Cheers
 
The chemical balance in the coco is critical in 3 basic ways. First the pH of the coco as a natural product is not ideal and must be adjusted. Second, the CEC spoke of earlier are not real CEC in the classic sense, because while they will loosely hold monovalent cation elements (ions with a single positive charge) on a matching negative charge, they bind more tightly a divalent ion such as Calcium or Magnesium making them unavailable to the plant, and they come and go as decomposition moves forward. Third, the give off of other ions by coco degrading upsets the ratio of the elements to each other causing many to become unavailable. The established buffer spoken of temporarily fixes this issue by filling the sites with divalent elements while stabilizing the pH at the range desired and setting the correct ratio of elements to each other.
 
@Camesino, agreed that I am VERY uncertain of my coco buffer and really hard to pinpoint this Dx while in 4th week of flower and all new growth has all but stopped, other than flowers fattening..:) So having to use what the girl has, leaf structure, color, pointing up/down and at my particular point in time, I am focused on, you guessed it, EC of inflow and runoff...LoL

My humidity is good with consistent mid-high 50's, temps, low 70's, highs 81. Hand water thoroughly 3x daily, small 1.5gal pots, 60/40 coco/perlite, drain to waste ~15% every time. pH always within 5.5/6.5, even when things get a little strange I will check pH runoff (not to match inflow) as a form of Dx'ing.

So as I have said, I am no spring chicken at this, but I have HEAPS more to learn as I got bored with just following labels, now I want to look at my girls and Dx them visually and say to myself, I need to drop Micro by .5mls or add a little more koolbloom, etc..:) So in essence I am NEW to this whole approach to cultivation and with that I am ok with the learning curve as well as screw ups..:)

My girl is ok, yes she took a small hit early on in flower, but all stable now, just looking outside the box at variables to help anyone with Dx'ing their girls.

Thanks..
 
Chefbjy, wow I am going to have to soak this in for a few..haha

So first, coco coir in its natural state (lets say the cheap brick kind) does not have a good pH, I thought I read something like 7.0 pH, so in essence are you advocating for not only pre-buffering the coco but establish a decent pH as well?

Your second point, are you referring to the natural tendency of coco to suck up the Mg/Ca from the solution leaving little if any for the girl?

I will need to think on and read more on the Third point, what comes to mind is the coco wanting to dump as much K as it can to establish equilibrium?

Apologies if way off base as I am determined to understand this, thanks..
 
OK, Well distribution isn't the problem if you are hand-watering.
Just want to toss a link to my Drip system here, because 3x hand-watering must be a royal PITA!
https://forum.growweedeasy.com/forum/growing-community/212796-campesino-s-automatic-watering-system

I suspect that the run-off being lower EC is an anomaly. I just communicated with another grower that had the same issue and they confirmed that it was temporary and has now stabilized at PPM +100-200 above inflow. The same thing happened to me. And when it happened, the plants that had gone "negative" EC on me were absolutely the healthiest of the bunch.

In my experience low run-off EC is a sign of a healthy plant. It is odd to be that low, but probably not a problem. I have no doubt that you will be monitoring closely and will see if any symptoms develop, but I would expect this to be a temporary anomaly.

Keep us posted!

Cheers
 
Standards are not absolutes but markers by which things are measured. A foot is a foot because it is known as a meter is a meter. In order to get the true picture of the condition of coco in EC and pH, it only works correctly one way and that is by the correct extraction method with Barium chloride in water. Barium, a bivalent metallic alkaline earth metal, strongly binds to the coco surface releasing virtually all previously bound cations: sodium, potassium, calcium, magnesium and ammonium if present.

The level of cations in a barium chloride extract is a good measure of the substrate quality at that very moment and a prediction of nutrients that were about to be released by the coco substrate making them available to the plants.

Measuring drainage or run-off alone will never be accurate. It may give the grower an idea based on experience but that is all. Knowing is growing and you should use properly measured coco.
 
Wait, Very UNCERTAIN in the buffer?
The buffer could still be the issue of course. I am curious now if you lowered the dose of CalMag a few weeks ago at the flip? And have you had any signs of Ca or Mg issues earlier in the grow? If the buffer is responsible for the lower EC, then I will recommend raising the dose of CalMag - back to Veg strength.
There would be no problem in doing this anyway, as long as run-off EC stayed low.
 
yes campesino recently explained to me the second and third point like this :
"The K issue in Coco is largely resolved if the Coco is properly buffered. It isn't a result of plant matter decomposing, rather the Colloids in Coco are loaded with K cations naturally, but prefer Ca and Mg. In the presence of Ca, the Colloids in coco will release their K and grab the Ca. But once the colloids are loaded with Ca and not K, it is no longer an issue."

also you should remember that all elements have different electrical conductivity so when in a solution a 1:1 ratio exange of ions may result in a rise or deacrease in EC;
potassium is half as conductive as calcium (http://periodictable.com/Properties/A/ElectricalConductivity.an.html) in fact thats why we have different TDS scales, NaCl scale is 500ppm=1EC and KCl scale is 700ppm=1EC witch means potassium needs more ions in order to register the same EC reading

heres a bit more about EC and how its scales: https://forum.growweedeasy.com/forum/growing-community/68078-very-important-to-everyone-ec-ppm
and here is the full info and a converter:
https://www.translatorscafe.com/uni...DS, parts per million, 640 scale/?mobile=1#44

i hope this helps (:
 
Chefbjy Could you provide a reference or link for the Barium Chloride treatment that you mention? Also the effect of Coco degrading (point 3 in post below). I would like to read what you are reading! Thanks!
 
Chefbjy Thank you!

We've got to keep in mind that this is from Canna, who are ultimately trying to convince you to buy their product. I have read some of their articles before, but I will review this.
 
Yeah, they are saying things that contradict other sources. It really does appear to be a marketing pitch IMO.

There is some good information there, but everything else I have read about buffering and the CEC is different from what he describes. The buffer can be upset, but this is why we always add CalMag to the water. The CEC, according to most sources, does not affect plant nutrition in Coco. The statement in the article that "...a prediction of nutrients that were about to be released by the coco substrate making them available to the plants." Suggests that Coco binds to nutrients and then releases them to the plant. This does not conform to my understanding of the CEC in Coco and its role (or lack there of) in plant nutrition.
Finally, while barium chloride may knock all other cations off the colloids (and provide the best buffer), Ca does a really adequate job of buffering the colloids in Coco. With Ca bound, no other nutrients that you add will upset that bond.
Degradation of the media should be slow by the time we are using it, but will upset the buffer. However, if adding Cal Mag to all water, this should be easily buffered as it occurs.
This is my understanding, but I learn more everyday! :)
 
Yes to my understanding the bond if not broken will continue to provide the correct nutritional balance. This is the harmony of calcium and magnesium with the coco releasing salt ions mainly potassium. It can also bond to n making for a hazardous situation.
 
Right, By buffering the CEC with Ca, you are essentially removing it from the equation. If they are loaded with Ca, the colloids do not interact with the nutrient solution. Plants then take what they need directly from the water and there are no nutrient exchanges with the media (ideally).

When it is not fully buffered, the colloids do make exchanges with the nutrient solution. These exchanges can affect run-off EC numbers
 
Oh yeah, trying to grow in untreated Coco would be chaos!

We see a lot of that actually in the sick plants forum. Usually Cal/Mag can help to fix, but the problems are not always related to Ca or Mg deficiency. All sorts of things can go crazy in untreated Coco!

The thing I don't like about the Canna article is that they are trying to convince readers that they are the only ones who know how to buffer and prepare Coco. It seems that they are almost intentionally being confusing to make it appear that it is more complicated and you will only have success if you trust them. The whole article seems to be leading to the last line where they say:
In the end, it is probably best to find a company with decades of research into coco, that provides correct solutions, and that introduced coco use into this market. Trust in the experience, use quality products that are well researched, and keep it simple.
Click to expand...


In my experience, you do not need to invest in these prepared products to get good results. I use cheap brick coco and my buffer seems to be very solid. Products like Canna save time and effort, but cost money. I think that for budget minded growers that are willing to get messy, Bricks are a perfectly acceptable option - if you rinse and buffer the coco yourself. If you have the money and want to save yourself from the hassle then get something pre-buffered.
 
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