Trouble with pH probes not working?

So i’ve now gone through two of these meters, assuming the first one was broken or dysfunctional and just bad luck. Now I bought a second one through a seperate company and am having the same problem. It does absolutely nothing :frowning: so confused because they’re both rated very well and loaded with positive reviews. To my knowledge i’m using it correctly, it’s not a very complicated process, probe down into soil with about 1-3cm gap left. The needle never moves regardless of the setting, moisture-light-pH, needle stays buried to the left. According to which would be “dark-dry-pH >8” Very hard to believe given my grow light is blairing and the soil is freshly watered. What the hell’s going on here haha, user error? If these meters are known to suck, i’d love some advice on alternate methods to monitor pH.

Here is a link to the device:

And here is a picture of my little sprout just for fun! Haha

Is the soil damp when testing?? Also, you can make a slurry from the soil and water and use your water pH meter if you have one. The probe ones like you linked aren’t very accurate

It’s not especially damp when testing no, but certainly shouldn’t measure as “dry.” You can kind of tell in the picture it has moisture. But even the “light” setting doesn’t move the needle, thats why i’m convinced it’s broken.

By “slurry” do you mean make a liquidy mud mixture from my soil and use a water pH test? I don’t have one of those either but believe you can buy disposable strips? Like something you’d dip in pool/river water to check? Recommend any tried and true brands of these? And thanks for responding.

The strips, drops, and even those soil probes are not very accurate. They’ll work, but you won’t get reliable readings.

Right now, the Apera phb3 is on sale for under $30 on Amazon.


Yes that’s what I mean. There is a good guide on the ILGM site.

Gotta get a water ph meter or you’ll be flying blind and have a lot of issues.

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Probes are never accurate because there is air space in soil and it is impossible to test ph of air. Must have water to get a reading but really the best way to test the ph of the soil is to do a slurry test or test your water run-off. To do a slurry test I use a 1:1 ratio of soil to water then use a ph pen to put directly into the mixture.

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I had my first one ever bought quit working so I got another one and when it came the switch was on and the batteries were dead. I went to dollar store got new batteries and it’s fine. Also some companies put a plastic strip inbetween the contacts where the battery is to keep this from happening

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Ive never used the strips, but i do use the drops and a BlueLab ph pen. Drops are as accurate as pen or better. I always double check with drops and they always read same as a calibrated pen.

Can this probe be calibrated? If not, you’re better off getting a pH tester that can be. Yes, they’re more expensive than the probe you purchased but the reliability justifies the price. My pH pen is 5 years old, is stored in probe solution, and I calibrate it regularly when I’m actively on a grow project. I think it cost me 50 bucks when I bought it but it’s one of the best investments I’ve made.

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Drops are subjective, though, relying on a person to compare what they perceive as a color against other colors. Therein lies the inaccuracy issue.

I used to use drops, myself.

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The drops themselves are accurate, not being able to perceive what color the ph indicates is user error . The drops indicate ph of 6.5 when ph is 6.5. If they were inaccurate they would indicate ph of 6.5 when its really 5.5. That would be inaccuracy. Theres more room for error in the pens being inaccurate then the drops being off on the readings. Plus, i dont gotta calibrate my drops. @blackthumbbetty

@SuperFlair I bought one of those probes when I first started growing NFG . Then I used the cheaper 10-15 dollar yellow PH pens and had 2 of them fail after a short period of use . I bought a Apera PH20 and it works fantastic . Worth the extra money for the peace of mind knowing its accuracy . If it was in question I have drops to double check . I don’t think the 3 way probes are very accurate . Sorry

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We just have to agree to disagree, here. Clearly, you don’t understand that human error is exactly the factor in reading drops. And also, they’re a pain in the ass if you need to take multiple readings w/in a few minutes’ time.


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Your making it out harder then it really is. Unless your color blind or something wrong with your eyes then its really not that hard to determine the color and what ph it is. Clearly you dont understand how chemical reactions work. If the drops say its 6.5 then ill bet my money its 6.5. The Manufactures of these drops arent spending millions to manufacture something that isnt accurate or doesnt do what it claims.Agreed to disagree.