Everything EC related

[Sockfilter]

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 DrPhoton ). 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..

[9fingerleafs]

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

[Sockfilter]

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..

[9fingerleafs]

yes, in my opinion you do not have a problem just a thirsty plant or a high temp/low rh environment (:

[Campesino]

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

[Campesino]

In my understanding, the processes through which plants adsorb nutrients do not have significant impact on the EC of the nutrient solution. When you plants are taking up the nutrients they are making exchanges which maintains an equilibrium. This is an area where I am working to deepen my understanding, but I do not believe that you can tell how much of the nutrients in the solution are being used by the plant without very expensive chemical analysis. This is ultimately, the main advantage of Drain to waste systems over recirculation. In recirculation, the EC stays the same (even rises due to evaporation), but the amounts of NPK etc are all decreasing through time as they are taken up by the plant.

When you are unsure about the buffer then I recommend maintaining full dose Cal Mag until late bloom. You should cut base nutes to create EC room.

Got to go check the girls

[Chefbjy]

There are many factors to consider in untreated coco the fact that it hasn't been bonded to ca mg can lead to it binding to a mobile nutrient like n since you had toxicity. The fact that there are holes in your profile are concerning but not a death sentence. The salt deposits can and will cling to the coco these salts(ions) aren't being evenly distributed which will have no effect on ec but will hinder the uptake of nutrients that are somewhat suppressed. To my understanding the inflow ec should be increased and as Campesino said with camg being a major part of your feed these nutrients are immobile and with k being a major ion dispersed in coco it will be harder to absorb the ca mg. Like I stated before it can also bond to n which is probably why you noticed the toxicity.

But if your distribution of wetting the coco is uneven it can deposit salts in the areas not being watered. I would think your outflow would be much higher if those areas were getting the right amount of water. But I'm new to this too so my info is based of google research. By no means am I educated in horticulture plant science or coco per say. I don't claim that I'm a scholar in botany or horticulture either. But I can read and write and process information that is pertinent to the subject. I will read more and deepen my knowledge as well 😉.

[Campesino]

I had to go back and re-read everything here because I think I have been partially confused as to the topic of conversation. I'm on track now...

I agree with Chefbjy , the colloids will do all sorts of exchanges if unbuffered and N can certainly be involved. I do think that increasing the dose of CaMg is the best course of action to satisfy the buffer in situ. I understand Chefbjy 's point about raising EC, but that does introduce other potential problems with osmosis (The main reason we measure EC) I suppose the the increase in EC caused by raising the dose of CaMg would be fine.

Sockfilter If the buffer wasn't causing problems earlier in the grow, I suspect that it will not be difficult to resolve the issues going forward, if you add more cal mag

[Chefbjy]

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.

[9fingerleafs]

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/...tivity.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...veryone-ec-ppm
and here is the full info and a converter:

https://www.translatorscafe.com/unit-converter/en/electric-conductivity/14-19/electrical%20conductivity%20unit-TDS,%20parts%20per%20million,%20640%20scale/?mobile=1#44

i hope this helps (:

[Sockfilter]

9fingerleafs, awesome info and thank you, yes I have read and continue to RE-READ Campesino's guides and info he spreads throughout the forum. Comes a point in time where I have to quit reading and tend to the girls, animals etc..

It's slowly sinking in.

As with most of everything, I learn best by actually doing it and making mistakes, as I mentioned above my goal is to not even need labels off of nutes, but to just visually Dx w/ EC inflow/runoff, and of pH in right range..


Gonna suck up some of this great info as fresh off the press for my eyes, I have noticed when I add Bloom or Koolbloom that the EC is not nearly as effected as say with the same volume of cal-mag..

"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/...tivity.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"

[Chefbjy]

Potassium is mobile and is always circulating.

[Sockfilter]

Campesino Chefbjy , excellent info in the sub-thread above guys and greatly appreciate it.

Yes Chef I am digging the theory that since I did not buffer properly that somehow the over abundance of N became a slight issue, for sure something I will go down the rabbit hole in search of more knowledge.

Yes Campesino, I do feel that is a safe course of action, I do feel that I was able to maintain a decent Ca/Mg level in veg, however that leaves me with the 2 prong question that I will have to figure out for myself, did I actually keep the coco CEC full or did I supply just enough Ca/Mg to supply a little to girl while the coco was robbing some of it? HAHA good question that I am sure we would all like the answer too..

So here is what I am playing with at the moment:

Lights on 2000, fertigate with 600 ppm (4.5ml calmag. 2ml Micro, 3ml bloom, 1.5ml koolbloom) pH 6.0, about 1 quart with 15% runoff, runoff last night was 560ppm.

0200- fertigate with 1 gal RO w/ 6ml calmag, pHd 6.0 about 1 quart (starting ppms lower than I wanted at 460ppm, gonna bump that up to match nute ppm of ~600) runoff was a bit higher as compared to inflow however I speculated it would be due to prior 2000 feeding with higher 600ppm.

0730- prior to lights out @ 0800, same as 2000 feeding, fertigate with 600 ppm (4.5ml calmag. 2ml Micro, 3ml bloom, 1.5ml koolbloom) pH 6.0, about 1 quart with 15% runoff, runoff this morning was around 610ppm, so finally seeing a slight uptick in my EC runoff..

So yes a little sideways on the feedings, yet I am dealing with a sideways problem..haha

I suppose I didnt really want this thread to be about a singular EC problem, however more of a go to thread for most EC related issues, however this topic may be a bit more than people are wanting to take on at the moment, So Thanks guys again for contributing..

[Campesino]

Sockfilter
The interval flush with "CalMag" water is not advised (The 0200 irrigation). As Chefbjy suggests you need to have a fairly high and consistent EC. You also need to provide the best nutrient ratio possible. This means Fertigate every time - don't irrigate with CalMag water.
This is even more true since your issue is EC lowering.
The #1 thing to watch for when raising EC is tip burn.

In answer to your Q above, I think the Coco and the plant have been competing for Ca. When you provide a full dose the plant is able to get some before the coco steals the rest. Eventually the Coco should become satisfied.

[Sockfilter]

Campesino, Sounds good nixing the cal/mag only and replacing with fertigation. I did just that last night as I was seeing much better EC readings as I make sure the EC inflow is consistent..

I recall reading that in your coco thread and there is some truth behind it gradually transitioning a plants EC intake..

[Campesino]

Yes, Nutes it all water is like point #2 in the guide! It is very important practice because it maintains a consistent root-zone EC. Eliminating the Low EC interval flush and fertigating always should really help correct your EC and buffer issues.

[FlyingDutchPaddy]

Hello good people,

EC/PPM measurements... always an interesting topic of discussion

From the discussions so far I've learnt a lot but the one thing that I was wondering about:
The nutrient schedule for recirculating setups as referenced here: https://www.growweedeasy.com/sites/g...t-schedule.pdf

It has the amounts of nutrients needed to add to water, but I suppose what is missing are extra columns for target PPM/EC , based on what plain water EC/PPM was started with as a reference.

Suppose after mixing the nutrients the target EC/PPM is still way off, what would you add to get the target EC/PPM ?