Accurate 8 soil PH Probe vs. slurry test - need some advice!

[Arthur]

Blue labs has one that'll do both that I've been looking at... but $$ it just sits there in my amazon wish list.... one of these days.

 

[Eyes on Fire]

ahhh,ok.I thought they were slamming you FOR using one.LOL I miss read that.No worries.Yeah it is ofcourse possibly its off somehow.But if it was the correct mix,and the PH was good on the base materials and mixed and watered right,you should not be having this problem.And you added extra Higher alkali materials too>I would go with the Slurry personally.But who's to say.how long you had the A8? ever take any real drops or damage at all?hmmm,not sure man.Not that familair with the coots mix.if I was truly worried and have room I would make another batch and combine them to help stabilize itself.the reason is,if you goo too far one way or the other its a constant battle of adding one at a time mixing and waiting.can become a real problem sometimes as well as takes weeks.LOL

 

[Waira]

.....OK marching on,...
About the soil "pro", if he's talking about the cheapo skinny probes you get for $13 at garden centers, he's right,...

-- what dropper test kit are you using, and what's it's resolution? This could be the tie breaker if it's good enough,...though color rendering with all that stuff in the slurry is getting iffy; I suggest you take the pH from lightly strained slurry liquid, like through a strainer/metal mesh type just to remove the bigger stuff..... As you know, the A8 is +/-0.2pH
-- assuming the pH meter is good, and the test drops test comes close, then the only conclusion I can reach is that meter is damaged or mis-calibrated.... send it back! Nobody said this is a fine, precision instrument! .... yes, the Blue Lab unit is tits, but it's also another bulb electrode unit to babysit and care for exactly the same as a pH meter (liquid only), because that's basically what it is! it too has a specific protocol for accurate testing, very wet soil for starters,.. the bulb needs to be fussed over and rinsed and cleaned using special solution to keep hazey residues from building up... just another PITA, IMO, that's why I haven't bothered to get one,....
--- do you have any other soil around, bagged, or even soilless/coco? A test of that may also help resolve this one way or another,....

My former grow client had a new one I got him, which I tested against mine, and they were within 1.0+ of each other,.... he stored his like shit though, and it fragg'ed a year later... mine is 4+ years and still works fine,... I also assume you're testing with it they way I mentioned earlier? Not in soggy soil, nor any sort of dry; tip is buffed clean; let it sit for a couple minutes to stabilize,....
So, all this has me wondering,.....I'll redo the tests again, at 1:1, then 2:1....
.... Hecno and EoF are better soil masters than i am, so whatever is happening with your home made stuff is best advised by them,....

 

[DTOM420]

.....OK marching on,...

About the soil "pro", if he's talking about the cheapo skinny probes you get for $13 at garden centers, he's right,...


-- what dropper test kit are you using, and what's it's resolution? This could be the tie breaker if it's good enough,...though color rendering with all that stuff in the slurry is getting iffy; I suggest you take the pH from lightly strained slurry liquid, like through a strainer/metal mesh type just to remove the bigger stuff..... As you know, the A8 is +/-0.2pH

-- assuming the pH meter is good, and the test drops test comes close, then the only conclusion I can reach is that meter is damaged or mis-calibrated.... send it back! Nobody said this is a fine, precision instrument! .... yes, the Blue Lab unit is tits, but it's also another bulb electrode unit to babysit and care for exactly the same as a pH meter (liquid only), because that's basically what it is! it too has a specific protocol for accurate testing, very wet soil for starters,.. the bulb needs to be fussed over and rinsed and cleaned using special solution to keep hazey residues from building up... just another PITA, IMO, that's why I haven't bothered to get one,....

--- do you have any other soil around, bagged, or even soilless/coco? A test of that may also help resolve this one way or another,....


My former grow client had a new one I got him, which I tested against mine, and they were within 1.0+ of each other,.... he stored his like shit though, and it fragg'ed a year later... mine is 4+ years and still works fine,... I also assume you're testing with it they way I mentioned earlier? Not in soggy soil, nor any sort of dry; tip is buffed clean; let it sit for a couple minutes to stabilize,....

So, all this has me wondering,.....I'll redo the tests again, at 1:1, then 2:1....

.... Hecno and EoF are better soil masters than i am, so whatever is happening with your home made stuff is best advised by them,....

Waira-

Lemme first say that I’m in NO way suggesting the A8 is bad. I’m just saying maybe MINE has gone bad. I always clean it after each use and my method of use was taken from the instructions and your instruction. I buff the tip regularly and I certainly did when I got these unexpected results. I’m wondering, and this is PURE and unadulterated guessing on my part, whether my use of Volcanite pumice stone as my aeration material in this soil is incompatible/problematic with the A8 sensor. The fact that it reads the soil is acidic, when there’s so much (too much) buffer in there, makes almost no sense. Especially a result as low as 4.0 and 4.4!

So now let me address the 2 OTHER test methods I used on each tote FIL of soil, BOTH of which produced nearly identical results. First, I performed multiple slurry tests using both distilled water and my RO water (66ppm at the tap because of our high PPM well water) that I PH’d to 6.5. These slurrys were mixed 1:1 soil:water and allowed steep for 1.5 hours. I tested them with a freshly calibrated Apera PH20 (bulb style) pH pen and the results are consistently 7.7 and 7.6. Don’t forget, this was a freshly calibrated and tested pen that’s only 4 months old and has read perfectly when put into test solutions since I got it and I store it and care for it meticulously. Still, I wanted to find a way to confirm whether my A8 or the Apera pen was throwing the weird result. So, next I went to the GH drops. It’s very hard to see color in a slurry mix but it wasn’t impossible to see the darker green tint that indicated an alkaline result in the range around 7.7.

So, clearly, MY A8 is either not working or there’s something (like those pumice stones) that’s throwing off the reading. Any idea on how I can test my A8 in another soil, to see if it’s accurate in other soils or has gone bad? Kinda thinking about testing a new bag of Roots Organic potting soil to see if it reads in the 6.5-7 range one would expect from a quality bagged soil. What do you think?

 

[BISCUITS]

It sounds to me this thing is only good for one thing and that is confounding the situation and is just another weak link in the chain if it’s unreliable.Test your pen against your pH solution in clear water so you can easily read the results and compare.In organics simpler is better IMO.If you really want and need a soil meter drop the coin on a blulab and be done with it.Good luck buddy KISS!

 

[DTOM420]

It sounds to me this thing is only good for one thing and that is confounding the situation and is just another weak link in the chain if it’s unreliable.Test your pen against your pH solution in clear water so you can easily read the results and compare.In organics simpler is better IMO.If you really want and need a soil meter drop the coin on a blulab and be done with it.Good luck buddy KISS!

I tested the pH test solution against the pH pen in clear water as you suggested and the results are consistent. I’m going to get the Bluelab probe as soon as I can afford it. Slurry testing is a PITA for regular testing or quick checks. Thanks brother!

I’m going to increase the base in my mix and reamnend to get it right. Just going to end up with more soil than I really need right now; but it’ll save me time in the spring. Just going to put it in a 50 gallon grow bag on a pallet outside.

 

[Waira]

...the pumice shouldn't be a problem, but who knows for sure? I do know the A8 spikes instantly when you insert it or move it, so something about that is tweaking the electrical conductivity differential between the two types of metal; maybe something about pumice/perlite is part of this? Chemically, they are inert, but physically (piezoelectric effect?).... All that you said sounds good mate, I think you have a defective unit, so send it back... If you have other soil around test it out anyway. You saw the results of the Roots soil, should be mid-low 6's,...

 

[DTOM420]

...the pumice shouldn't be a problem, but who knows for sure? I do know the A8 spikes instantly when you insert it or move it, so something about that is tweaking the electrical conductivity differential between the two types of metal; maybe something about pumice/perlite is part of this? Chemically, they are inert, but physically (piezoelectric effect?).... All that you said sounds good mate, I think you have a defective unit, so send it back... If you have other soil around test it out anyway. You saw the results of the Roots soil, should be mid-low 6's,...

Thanks brother! I’ll see about sending it back if it tests weird on the Roots soil. Only real reason I thought maybe the pumice is that it’s a volcanic rock, I believe; and volcanic rock has been known to (sometimes) be slightly magnetic. IF, there’s some charge in the pumice, that’d really throw it off, no?

Anyway, problem solved. I spent the afternoon mixing more soil with NO additional liming agent; and I mixed it with the original batch I tested. This SHOULD bring me in line, precisely, with the original recipe. I’m going to scratch together the money and send a sample of all this soil to Logan Labs to see how it all tests. I now have about 70 gallons of pretty premium totally organic soil sitting in a 100 gallon smart pot outside. It’s going to sit and cure it’s way to the spring planting. So, it ought to be pretty stable by then.

I seriously considering getting one of those Blue Lab soil ph units. If I can’t get a warranty swap on the A8, imma sell something to scrape the extra hundred bucks to upgrade. They have a good warranty and are so well known for their accuracy it would be a great investment.

Thanks again, bud!