Which is what I do. But obviously not by adjusting the pH of the water. That's meaningless to the pH of the substrate.
Waxy looking plant: what is causing this? Would love some input
- Thread starter Jame9111
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i hear what you're saying. the difference is in the method. i do it on the inputs / flushes / and never monitor outputs or do a slurry.
i think you're working it from the opposite end. which only shows there's probably more than one approach, and may only add to the confusion lol
Emilya Green
Well-Known Member
Didn't we establish that his nutes auto ph? Here we go again.
You're in hydro so you have to work from input. As proven by slurry testing, changing the pH of the water will not change the pH of soil or ProMix. Within 60 minutes the pH will reflect the medium not the water. Probably less in a potted plant, since we're not adding enough water to make mud.
Anyone having a pH problem in soil or ProMix is having a pH problem of the soil or ProMix, not a problem with their water. Roots see the pH of the substrate in under an hour.
This isn't anecdote or experience, it's science.
Emilya Green
Well-Known Member
Yeah bro, science.
Are you saying that slurry tests are worthless to measure the pH of your substrate?
Emilya Green
Well-Known Member
once again, yes... these are closed containers, not farm fields. The pH of the water rules in this environment. None of your cited "science" discusses closed containers. Unless you have some new information, you have not yet been able to convince me that you are right.
lol. yes. but he was ph'ing regardless. at least that's what i got out of it..
the other thing is the poor guy seems to be watering it almost like coco. the plants are doing great but something is weird. i've more or less been saying just keep going as there doesn't seem to be any pressing issues.
we were hp/sunshine based for the med grow. we didn't slurry, except in the very beginning. the results just weren't consistent. otherwise i used to chase output. i remember having to ph up a couple times as we treated it closer to soil. ph related issues crept up when running lower.
less than 20 miles away, on a different water source, it was usually treated like hydro. we couldn't run their way successfully and vice versa. also we didn't need ro, and they did.
the 5.8 you cite suggests it balances to hydro ph which is what i would consider perfect for soilless.
which begs the question .. if ph doesn't matter, does it matter if you ph ?
initially we didn't ph at all, nor did we start as a plan. we ph'd as it worked under those circumstances. all we knew was the read on the plants, and that a flush and reset didn't quite catch it. also noticed the sativa were less prone.
A slurry test is performed in a very closed container. It changes the pH of the water to the pH of the substrate in under an hour. And that's using so much water that the result is mud.
The pH of the water does not rule anything. The pH of the substrate does. Only in the 60-minute (or less) window do the roots see any different pH from the soil.
For example, Hanna Instruments (they make lab quality pH meters) recommends 30 minutes before testing the slurry. Another industrial meter company (Cole-Parmer) recommends an hour.
Here's how it works in practice: I take the substrate and add distilled water (pH 7) to make a muddy slurry in a measuring cup, which is a lot more water than we retain in our pots. Within an hour, the slurry will be the pH of the medium, not the water. That's how quickly soil buffers water pH. In an hour my slurry dropped from 7 to 5.8.
Even in a small container that is actual mud (which is not what our pots look like after watering), the pH of the water becomes the pH of the soil within 60 minutes or less.
It took a while of watering with an 80/20 mix of nitrate/ammoniacal N to get that back down from the 6.8 it has risen to. This is why I'm not using ProMix at the moment.
Only in hydro. As I've mentioned, anyone who wants to pH their nutes can certainly do that if it makes them comfortable. It will not change the pH of the substrate as shown in slurry tests in closed containers. The roots will take up the nutrients at the pH of the substrate.
that's essentially what i meant.
to confuse things further i've grown outdoor in hp and i never ph anything outdoor. no problems. indoor and under light, it has always seemed to need it at some point.
Emilya Green
Well-Known Member
Sorry bro, but you are once again making unsubstantiated assumptions about comparing a lab experiment to what happens in a closed container of soil. What we have in our containers is not a pure and consistent slurry in a small well mixed closed container. We add 10lbs of water to 1 or 2 lbs of soil and because Gravity still works, it gathers at the bottom of that container where the big feeder roots are, and it is much less of a slurry down there than it is a light soup, maybe even a brew. The assertions that your "science" makes about a slurry, are not at all true in real practice, down in the bottom of the container, where it counts, What you have down there where the roots are is not at all a well mixed slurry of equal amounts of soil and water like you have in your slurry test, and because the water down there outweighs the soil around it by many fold, it has by far the most influence on the pH. In that environment (again, where it counts) the pH is much closer to that of the water/nutrient mix. At that moment, the pH of the liquid is indeed starting to drift because of the medium trying to influence it, but that is a very much slower process since the soil is not being manually mixed into the slurry as in your rapid pH change experiment, the soil has a cohesion that doesn't allow it to mix in such a way with the water, so you get more of a flow through effect rather than an immediate conversion. It takes time for the buffers in the soil to influence the pH of the liquid. Think of the environment down there below the water table as a well populated solar system with cohesive chunks of matter here and there, but mostly vast spaces of nutrient water in pathways and oceans between them. The feeder roots exist in this environment, mostly influenced by the water flowing through those areas. It has to be. The engineering 10:1 rule says it must be.
Please don't leave your pots sitting in watery soup. It can lead to wet feet and cause nutrient uptake issues. Proper drainage is important to potted plants. At no time should the water content of your soil be anything close to a slurry anywhere in the pot.
Here is a paper from Cornell on the importance of testing the pH in containers and how to correct it:
It's probably going to get taken down since we're not supposed to link to pdf files, but I don't want to post all 9 pages as images as the site would prefer.
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Jame9111
Well-Known Member
Well said
Any media that is peat-based will need to be amended, either at the factory or by the gardener, as the pH of peat is quite low, something like 3.0 to 4.0, and if one's soil (as in what's in the ground outside) has a lot of peat in it, it'll often test at 4.5 to 5.2.
As has been mentioned, lime is commonly used. It's been years since I had to
I used to throw a handful of pellatized lime into a coffee grinder, turn it into a powder, and add a tablespoon per gallon of my (commercial) soil mix. But I've no idea whether it did anything useful. Made me feel like I was doing something
.
When did we get all the twemojis.
Emilya Green
Well-Known Member
you won't explain how this fits into the present argument, in your own words, but you want us to read it anyway because it is long and important and just the act of presenting it to us makes you look like you know everything there is to know about his subject, and that you are right in every respect. Just read it! Then you will understand! Got it. Not sure yet what all this has to do with a grow that doesn't need to worry about pH, but I surely am impressed.
You claim that pH in containers is different from open land, I give you a university study that is specifically about container studies that mirrors the studies on open land that you claim aren't relevant to containers.
Yet the information is exactly the same, from the testing to the results of pH swings to the methods of correction. Same in containers as open land.
In containers they waited 60 minutes for the pH of the water to become the pH of the soil. Not only that, but in their pour-through method they are measuring the pH of the water coming out of the very bottom of the container, the water you claim will be most resistant to this change.
If you choose not to read the evidence it doesn't mean it's not relevant. Most folks who are curious will read information to broaden their perspective.
Feel free not to read it if you're not curious (though you did ask for "new information" above), but the information is out there.
Yet the information is exactly the same, from the testing to the results of pH swings to the methods of correction. Same in containers as open land.
In containers they waited 60 minutes for the pH of the water to become the pH of the soil. Not only that, but in their pour-through method they are measuring the pH of the water coming out of the very bottom of the container, the water you claim will be most resistant to this change.
If you choose not to read the evidence it doesn't mean it's not relevant. Most folks who are curious will read information to broaden their perspective.
Feel free not to read it if you're not curious (though you did ask for "new information" above), but the information is out there.
Emilya Green
Well-Known Member
closed containers vs open containers... yours is a greenhouse study presumably with large open containers of soil being used over and over again, and it bears very little resemblance to a 5 gallon plastic bucket of one or two use soil that is no need of "correction." Even though you can't see it, it's still apples and oranges
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