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

[Olderfart]

:smoking: Cheers OF! The original posting was here before I came I think? Since then, after working Sick Bay for years, I added some extra tricks to it to help get it more accurate and "user friendly"...
I've tried a long while back to do direct comparison, I forget the specifics but I think with the then decent Accurate 8 soil pH probe it was still over 0.5pH off, in real soil-- not soilless! That caveat, particularly with coco is important I think with soilless, and it's less influential mix of components, could be more reliable, if those were run like they should be (frequent weak inputs, lots of run-off)...
But you're right, it's a "lesser evil" option! So much error potential due to the human, technique and equipment factors, magnified by the ham-fisted calculationals....At some point I just told folks to use it as a rough gauge to see how badly off pH things may be, so if it comes out at say 5.2, accurate or not, close enough to say it's too acidic in there and thus needs a corrective flushing at the least...

I loved my first two A8's, I tested those against slurry testing and they were within reasonable error margins (0.2-0.3)... This new one is dogshit right outta the box, just WTF wonky off too! ... It was so handy and easy, but now it seems it's time to cough up the $$$ for a "pro" unit bulb-type, and another bitchy sensitive piece of equip' to nurse along exactly like a pH meter, since they are the same damn thing! That Blue Labs unit is sweet though, made for such in-pot checks unlike a regular meter type... Another reason I've swung to mostly organic grows, "super " soils and supp's. this year I hardly bothered with pH checking after digging up a couple slurry runs, which is fugly shit on the roots in a tight stuffed pot!

This issue is one of the reasons I may be heading to living soil as well - if my second attempt does not turn into another shit show.

I considered the Accurate 8, but am not sure that I trust measurements in the top couple inches of the pot. That location may not have a lot of relevance to the main root zone, especially in autopots. I also had a look at the Bluelab. Although it gets a bit deeper, it still doesn't get all the way in. Also, the meter is bloody expensive, and I can't get my head around how in hell this unit manages to protect the sensor surface from soil abrasion. Sticking a pH sensor into a mix of soil/medium with perlite seems like a recipe for killing the sensor to me. Do you know anyone who has had good luck with the Bluelab in the longer run? I could almost suck up the cost if the damn thing could be expect to last for five years, but not for two. With luck, the soil option will remove my interest...

Did you get around to trying those Dinafem CBD seeds yet? Happy growing @Waira.

 

[Waira]

The A8 probe is nearly 10" long, the A7 is the stubby one....(snicker!)

BL's isn't that long, but enough I'd say in most cases... It does have a pointy sleeve that's used to protect the fragile bits when penetrating the medium, no worries there...
The electrode is replaceable too I think.

I did mate, 2 in fact... Alas, one went sideways by 2nd set of leaves, the other struggled and didn't finish well.. I'll try again next season! :smoking:

 

[Olderfart]

The A8 probe is nearly 10" long, the A7 is the stubby one....(snicker!)

BL's isn't that long, but enough I'd say in most cases... It does have a pointy sleeve that's used to protect the fragile bits when penetrating the medium, no worries there...
The electrode is replaceable too I think.

I did mate, 2 in fact... Alas, one went sideways by 2nd set of leaves, the other struggled and didn't finish well.. I'll try again next season!

Hmmm. All three of mine this summer were runts, which I blamed on the soil. Do you know whether bcbudlady grew any? Have you heard of bad results from seeds produced from two separate plants, one reversed with CS, the other with two pollenated branches. I'm planning on a multi potter with two or three of those girls in my imminent grow. Fingers will be crossed, I hope I don't end up wasting one of my four pots... :smoking:

 

[DoobieGrows]

So my

.... 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

So my in feed was 6.0. I just tested my runnoff and it came out as 6.5. So +.5 difference. So 6.5 + .0.5 = 7 as actual media ph?