another quickie reference for run-off testing, and pH estimation...

[HashMaster]

That is why I call @Waira the guru....what a font of knowledge........


@HashMaster, personally I never drown my plants, they can get starved of oxygen and it stunts the root growth. Let them search out the moisture some times....

Your too fast for me eP !

I deleted my own question because as soon as I typed it and hit post I realized the answer.

Say what you will about little wings and funny feet, you be one fast penguin !

 

[easternevergreen]

@Waira
If you'd be so kind as to check out my grow journal in the indoor section labled first indoor/auto grow, id be much obliged. It'd tell you my supersoil recipe, and show the Bloom nutes I've been using.
Been using higher doses of the Bloom nutes, as prior to this, they had been drinking it down with no problems.

I have a rapitest mini pH tester for soil. It's analog. Not sure how it's powered, or of its accuracy. But, I have the drops, so I'll have to try the method prescribed above and report back in an hour.

 

[Cat]

.... posted here for fast access and reposting where needed, for those without a quality soil pH probe,....

...The Pour Thru (run-off) Method for Testing Container Media:

* first, test the pH of your usual water source*
1. water containers to saturation (so that a few drops of water come out of the bottom of the container) with the normal irrigation water they have been receiving... do not use a nutrient solution, it will badly skew the results...
2. after container has drained for one hour, place a saucer under the container -- make sure to use a clean, uncontaminated container- any residuals in dirty one will skew the readings,....
3. pour enough distilled (DI)/RO water on the surface of the container to get about 50 mL (1.5 fluid ounces) or so of leachate to come out of the bottom of the container (Table 1)
4. collect leachate for pH and EC testing;
5. calibrate pH and EC meters, if not done recently
6. measure pH and EC of samples, then do this calculation-->

-- Calculation ->>> If your runoff pH is higher than your starting (water) pH, use this equation to determine your soil pH:*
Soil pH = Runoff pH + Difference

--- If your runoff pH is lower than your starting pH, us this equation:
Soil pH = Runoff pH - Difference.

For example, say your the starting pH of your solution before it goes in is 6.5 and the pH of your runoff is 7.0. The difference is +0.5, so using the above equation:
Soil pH = 7.0 + 0.5*
Soil pH = 7.5

If your starting pH is 6.5 and your runoff is 6.0, your difference is -0.5 and using the above equation:
Soil pH = 6.0 - 0.5
Soil pH = 5.5

hI @Waira This is a great guide for testing run off, but I wondered if I should follow the same system for coco. I thought that flushing coco with just water is not advisable, but I'm prob wrong. Do you know what the ph of coco run off should be?

 

[Waira]

:smoking: Hey Cat-- Thanks bro' but I can't take actual credit for it, just some tweaks to the steps,... You're right, coco can't be tested doing this method, it'll mess with the CEC balance in coco I believe,... Now, as an outdoor grower, I haven't used coco since it's not the best choice for this, so I can tell what I've read and learned from other coco-nuts- Have you poked around the coco forum yet? The article I read about this said to use a 150ppm Ca-Mg + a 150ppm nute solution, pH'ed to about 5.8 (higher if Ca defc.?), and pour through enough soln. until the run-off is at or near the same pH and ppm going in,... now that said, in soil or coco, the straight run-off isn't an accurate enough measure of the pH, especially if you pH'ed the water going in or used nutes,.. as you see in this guide, the final pour through calls for RO/DI water (and therefore no buffering minerals), so after that hour long soak using your normal pH'ed water, things have stabilized and are a fair rep' of the current pH, without adding more buffering minerals in and skewing the results,...

 

[Cat]

:smoking: Hey Cat-- Thanks bro' but I can't take actual credit for it, just some tweaks to the steps,... You're right, coco can't be tested doing this method, it'll mess with the CEC balance in coco I believe,... Now, as an outdoor grower, I haven't used coco since it's not the best choice for this, so I can tell what I've read and learned from other coco-nuts- Have you poked around the coco forum yet? The article I read about this said to use a 150ppm Ca-Mg + a 150ppm nute solution, pH'ed to about 5.8 (higher if Ca defc.?), and pour through enough soln. until the run-off is at or near the same pH and ppm going in,... now that said, in soil or coco, the straight run-off isn't an accurate enough measure of the pH, especially if you pH'ed the water going in or used nutes,.. as you see in this guide, the final pour through calls for RO/DI water (and therefore no buffering minerals), so after that hour long soak using your normal pH'ed water, things have stabilized and are a fair rep' of the current pH, without adding more buffering minerals in and skewing the results,...

Thanks @Waira that makes sense

 

[GoAuto6]

There's some good reading in here....
https://www.autoflower.org/threads/ph-potential-hydrogen-the-manual-polled.12594/

 

[Cat]

There's some good reading in here....
https://www.autoflower.org/threads/ph-potential-hydrogen-the-manual-polled.12594/

Thanks, I'll have a look at that

 

[The Plant Whisperer]

No offense but it has been proven time and again testing runoff is like taking a dump and staring at it a couple seconds and telling what you had for breakfast.Been there done that and found absolutley no common ground checking runoff and ppm.here are way to many variables that can effect soil PH as the water runs through it.One especially that soil has a natural buffer and whatever you put in can be 2 points off in either direction depending on salt build up in the soil etc.I have tried this numerous times and finally accepted the fact your chasing your own tail.
Out of 12 plants i did this on repeatedly numbers were all over the place and the healthiest plants wouold have the strangest numbers that were to far apart to nail down any kind of consistency to the plants that were struggling.
than to make matters worse adding PH up or down in the dirt will not change the soil PH.you can add 10.0 PH and after an hour the PH will go right back to where it was.Lime is really the only reliable way to change PH and it takes more time than 1 grow to alter the soil PH.
If water PH affected soil than everywhere it rains 7.0 neutral rainwater the PH would be 7.0
to many variables involved that affect PH like composted materials and nutrient levels.
If your soil PH is 10.0 and you add 6.5 to it the water coming out will be no where near 10.0 and will give you a very off reading that is a fact.
The only reliable way i know to test soil PH using a PH pen is to dig soil from the root zone and add to a cup 3 part water 1 part soil after the soil has been dried for 24 hrs.Pour in distilled water or RO water and let it sit for 24 hrs.pour thru a coffee filter and check it. this will get you close.
The PH probes are junk all it is to it.we used em planting bean fields and had soil tested by farmers co op and them probes are so far off.AG lime took months to change the soil especially very acidic soil around pine tree areas.Best way is to ammend your soil before you plant and get the PH right and forget about runoff.Also the more drainy the pot the more it will affect the runoff.Soil that drains slow will give you a completely different reading,
Personally i think testing runoff might help people sleep better and maybe make us think were doing some great but in reality its doing Nothing but making us add unnecessary crap to our pots.

 

[Waira]

Right, the run-off test is lousy in general, that's not news to many of us,... I tell folks all the time it's a crude estimate at best even when done according to this protocol, and next to useless when done wrong,... But when there's a grower without the experience, expertise, and equipment who has a serious problem, and fixing it RIGHT and fast depends on some sort of decent pH check, this must serve, sorry substitute as it is,... if 7.0 water goes in, and 5.5 run-off comes out, at the very least it indicates that the soil is badly off enough in pH to affect the water that quickly and severely... if it's causing defc. symptoms by lock-out or toxicity, then we know that some sort of correction, even flushing (a lesser evil) is mandatory before anything else can be done.. Adding more nutes would FUBAR things even worse, right? We don't want that to happen, so we do what we can by remote here to help save their plants,... I have also tested this method, and found it dicey, but close enough to get a good enough picture to recommend some sort of action,.. So far, zero people have come back here to bark and foam at the mouth over ruined plants that were caused by genuinely bad advise... believe it, after 2.5 years here in Sick Bay, such poor results would be glaringly obvious!
Aside from a professional soil pH probe and skill at slurry testing, folks have few decent choices for this,...and who would ever recommend gouging out a fat scoop of root packed soil from a pot for testing anyway? ... Right-- most cheap probes are indeed crap, something else I always caution; I do recommend the Accurate 8 because from my testing vs. a pro-grade pH probe, when used properly it gives a pH reading within a few tenths, again decent enough to be of true help in determining a course of action... there many here who can testify to this,... And I make no claim to be some sort of Canna' grow-god either, BTW,...
pH adjusting water is not a waste of time, particularly when considering cumulative affects, and not forcing the soil/soilless mediums' buffering to carry all the weight.. it's preventative more than curative, that much is true,... Rainwater-- bad example again... do you know what the actual pH of rainwater is, and why? Usually, it's under 6.0, caused by CO2 dissolving into solution and reacting to form carbonic acid... do you know why it's so easily affected by such tiny amount of CO2? If want to make factual points on things you need to present factual examples and analogies, otherwise it's difficult to accept your conclusions with any seriousness,...
you cite meaninglessly extreme examples here: you add 10.0 water (lye basically, right??) to any soil and it'll FUBAR that soil instantly, along with the plant, and it won't correct much if any under such a magnitude of basic soln.! ...Sorry but that is patently wrong,... And what's with the 10.0 soil pH example? You pour 6.5 pH water through it and that water will be profoundly changed in pH, and such an extreme pH would make any-run-off test useless, so.... right! what's your point here?
Agreed, amending with fine grade (limestone type) lime first is always best, no news there,... top dressing with it is not very effective, and it's not recommended for fast action,... dolomite, which is chemically different from true limestone, is the slowest of all limes, and it's this chemistry difference behind the why, especially if it's any sort of course in grade...there's a world of differences between a small pot of man-made soils and soilless mediums, and the vastness of actual native or Ag' soils, so not a good comparison there either,...

 

[Duggy]

No great claims are made regarding the accuracy of the above test. As the title states it is purely for pH estimation where problems are already occuring and some idea of pH is necessary to determine a starting point for the required course of action...