Coco help please.

[Ca++]

I am pretty sure my Hanna is 700 scale. HI 9813-6 ?? My ppm reading less than 2x the ec reading.

what does this mean?

• "Variable EC to TDS conversion factor: The conversion factor automatically adjusts from 0.56 to 0.78 based on actual conductivity

Conversation usually revolves around a conversion factor of 500 or 700, which suggests a linear relationship between EC and PPM. It's not.

Calling it TDS, means it is the 500 scale. That is the conversion from EC to TDS. It's converting to PPM where you might find 500 or 700.
EC 1.0 is 500 ppm tds. However, EC1.5 isn't 750ppm tds. The relationship isn't linear, and here your meter is telling you how accommodating it can be. Looking at the EC, and modifying the tds reading, away from 500:1 as needed.

It is all far too complicated. Peoples heads are exploding everywhere already. We are horticulturalists and use EC. Because nobody even wants to understand ppm measurements. I wouldn't of got this far, had you not of asked. It's an unnecessary evil, from when the fish tank industry was supplying us.

The pro sets his tank, weighing in powders of different compositions, that may be a mix of things the plants wants, but will also be adding things the plant won't. He will get to the PPMs he wants, using his powder scales. Literally weighing powders into a known volume of water, to know the ppm through calculation. If a perfect meter existed, he could than add up his total, and... the meter would still say something else. It's all them unknown impurities, of unknown conductivity it can also see, not just the feed.
All the grower can do, is make up the tank, then measure it's conductivity. It's EC. Then over the coming days, that conductivity/EC measurement offers insight as to how much the tanks composition has changed.
It's absolute folly to try to convert this conductivity reading to PPM, with any maths. As an example, you would have to take out twice as much K as Ca, to get the same shift in reading. 50ppm less Ca looks like 100ppm less K, to any of these meters. They don't know what they are looking at. It's so fundamentally floored, that's it's just wishful thinking.
Only EC is real. It's a measure of the tank, not a guess of what might be in it. The rest is literally a poor interpretation, of EC. So why bother. I just don't need to know all this, except to understand that shared ppm figures offer me no understanding of what's going on. They are, in fact, hiding the truth.

The EC conversation is extremely short. Like.. plug it in. Now it works.

Edit: Just one more, before I give up.
I can make my tank to EC 1.0 and my EUtech will say 700ppm, and Hanna 500ppm. Any EC meter will say 1.0 so how should I publish my tank strength. Is it 700 500 or 1. That 700 is 40% stronger than the 500. How should I explain my tank. 700 500 or 1

 

[Ca++]

I root cuts around half strength. You shouldn't go lower with asian coco. There is too much sodium salt in it, which the plant will take preferentially over K. We must put in enough K to keep it's number far enough ahead. There must also be enough Ca and Mg, as they must displace that sodium and K in the cec exchange, to see it leave as runoff, and combat the dominance of sodium and K in the cec. Just to keep the feed balanced.

Cannabis can take full light at an early age, and with full light, we need full feed, to fuel full growth. If they are actively growing, then holding out on food and light offers little purpose.

I root around half, and then start around 75-80% but it's soon 100%. Seeds like a softer start, but look at soil grows. They can go straight into final compost most of the time. No need for reductions. I do seeds in general purpose, and find actual seed mix to be of little use. Our plants are fast growing things, that need support.

 

[ResinousKingpin]

You are right in what you write, but it also depends on the variety we grow. If, for example, I gave half the dose to start growing from seeds, to a Sativa that does not tolerate large doses, I would simply burn it. I always start at low EC and slowly bump it up.
The most important thing is to observe your plants and whether they like a large dose of fertilizer. If the plants like it, you can go for 150% of the full dose. However, I still believe that it is better to add less than to overdo it.

Regards!

 

[Rocket Soul]

Re using strong nutes with seedlings: there seems to be two camps regarding this, some seem to be able to make it work. In our grow we tend to give extra strength feed the first time after transplant to get the coco buffered somewhat; weve had better results doing it that way since high CEC coco seems to like to hold a lot of Ca and mag. Please dont ask me for details though cause i dont quite understand it myself, only that it seemed to work in our canna coco. I think it depends on what runoff you get just from flushing your brand new coco: some come buffered some come un unbuffered and some come with lots of sea salt (avoid this coco as its not really good)

In general i would advice to allways measure your runoff ec/ph ause this will give you an idea of what the roots are actually getting. This can be done individually or by tray; individually would be indicated if there is just one plant thats having problems.

 

[Orange's Greenhouse]

Well, it's best to avoid hard water altogether. Though I have to say that GH hard water formula works for me. The city and their lab agrees with my primitive measurements. But the point is, a meter is unnecessary unless using a reservoir, and even then it's not really needed if you have the pH indicator dye to keep that in line.

Any smarts I have revolve around spelling and knowing that advice is to be avoided. The plant is the meter. I've been trying and trying to help people here by telling them that helping themselves is the way to go - they need to stop listening to people, watching videos, trying to copy things that will be detrimental in their particular situation.

The best help that can be given to the nonprofessional grower is a few pages from a random 80's book on houseplants or (outdoors) gardening. Throw in pH 6 is good for hydro growers, and any additional little tips are learned from experience and could be said in fewer words than this post.

So you tell people to not listen. But why would they listen to you?

Your approach is just wrong. I read guides online, got cheap horticulture nutes and a good meter. I had zero fertility related issues in the first 4 grows.

 

[Orange's Greenhouse]

Conversation usually revolves around a conversion factor of 500 or 700, which suggests a linear relationship between EC and PPM. It's not.

Calling it TDS, means it is the 500 scale. That is the conversion from EC to TDS. It's converting to PPM where you might find 500 or 700.
EC 1.0 is 500 ppm tds. However, EC1.5 isn't 750ppm tds. The relationship isn't linear, and here your meter is telling you how accommodating it can be. Looking at the EC, and modifying the tds reading, away from 500:1 as needed.

It is all far too complicated. Peoples heads are exploding everywhere already. We are horticulturalists and use EC. Because nobody even wants to understand ppm measurements. I wouldn't of got this far, had you not of asked. It's an unnecessary evil, from when the fish tank industry was supplying us.

The pro sets his tank, weighing in powders of different compositions, that may be a mix of things the plants wants, but will also be adding things the plant won't. He will get to the PPMs he wants, using his powder scales. Literally weighing powders into a known volume of water, to know the ppm through calculation. If a perfect meter existed, he could than add up his total, and... the meter would still say something else. It's all them unknown impurities, of unknown conductivity it can also see, not just the feed.
All the grower can do, is make up the tank, then measure it's conductivity. It's EC. Then over the coming days, that conductivity/EC measurement offers insight as to how much the tanks composition has changed.
It's absolute folly to try to convert this conductivity reading to PPM, with any maths. As an example, you would have to take out twice as much K as Ca, to get the same shift in reading. 50ppm less Ca looks like 100ppm less K, to any of these meters. They don't know what they are looking at. It's so fundamentally floored, that's it's just wishful thinking.
Only EC is real. It's a measure of the tank, not a guess of what might be in it. The rest is literally a poor interpretation, of EC. So why bother. I just don't need to know all this, except to understand that shared ppm figures offer me no understanding of what's going on. They are, in fact, hiding the truth.

The EC conversation is extremely short. Like.. plug it in. Now it works.

Edit: Just one more, before I give up.
I can make my tank to EC 1.0 and my EUtech will say 700ppm, and Hanna 500ppm. Any EC meter will say 1.0 so how should I publish my tank strength. Is it 700 500 or 1. That 700 is 40% stronger than the 500. How should I explain my tank. 700 500 or 1

It's even more complicated than that. As the concentration of salts incrases the EC does not increase at the same rate. So 0.75 mS/cm might be 1 g/L NaCl but 2 g/L NaCl is not double the EC but 1.43 mS/cm (90 % increase). Different elements have different effects on conductivity. 1 g/L Mg is 2 mS/cm while the same concentration of Ca is 1.6 mS/cm. For complex mixtures, with many different ions the total is not the sum of it's parts.
So EC is really handy because its easy to measure. When comparing solutions of the same composition the higher numbers means more concentrated. But that is about all it tells us.

It does not say what is in the solution, eg when switching fertilizers or recirculating systems. It does nothing regarding uncharged species, such as exudates, that are relevant because of osmotic pressure. Also it's pH dependent. Afterall pH is just the concentration of hydrogen ions, which are highly mobile and contribute hugely to conductivity.

 

[Ca++]

It's even more complicated than that. As the concentration of salts incrases the EC does not increase at the same rate. So 0.75 mS/cm might be 1 g/L NaCl but 2 g/L NaCl is not double the EC but 1.43 mS/cm (90 % increase). Different elements have different effects on conductivity. 1 g/L Mg is 2 mS/cm while the same concentration of Ca is 1.6 mS/cm. For complex mixtures, with many different ions the total is not the sum of it's parts.
So EC is really handy because its easy to measure. When comparing solutions of the same composition the higher numbers means more concentrated. But that is about all it tells us.

It does not say what is in the solution, eg when switching fertilizers or recirculating systems. It does nothing regarding uncharged species, such as exudates, that are relevant because of osmotic pressure. Also it's pH dependent. Afterall pH is just the concentration of hydrogen ions, which are highly mobile and contribute hugely to conductivity.

Yes, all our feed meters can do, is measure the tanks resistance. Which can help us replicate things, or show us trends. It's a very rough guide, and not meant to be a measure of anything, except resistance.

It is so rough a guide, that we are happy to see 1.5 on an EC meter, until it's 1.6 with nothing in-between. However, that would be about a 7% difference, before it's worth reporting. Sometimes we might be mixing a tank to 1.0 and so, the next change in reading is when it's moved 10%. This is the kind of accuracy that will suffice. Better meters might do 1.00 and so we have a 1% resolution, but it's getting a bit ahead of the meters capabilities. As you say, so many things can tip the reading, that differences of 1% are perhaps not the feed changing. It's just a rough measure, from a 2$ meter, not a lab boiling off the water to retrieve the solids for analysis.

The idea someone would want to take the EC figure, and try to use it for a PPM calculation, is a bit bonkers. We just have too many variables. To then offer their result to a 4 digit sum, is like 0.07% resolution, where 7% is considered enough. Made up figures don't need that sort of resolution. It gives an illusion of accuracy, and people will try and chase that, thinking it's real. It's like the 0.000 pH meter. When 0.0 is enough. It's creating work for no reason.


If it at least looks like we know what we are talking about, perhaps I'm done here. Even if one person leaves PPM for EC, it's a step in the right direction.