How accurate are cheap pH meters?

[Upstate12866]

Hi,

I got some pH strips to test that my Star San solution stays under 3. I find the strips a little difficult to read (is that orangish color 3 or 4?)

I won't be buying a very expensive meter but I might buy a cheaper one. I am curious if anyone has experience with these $10 Amazon "pen" models.

The cheap models claim 0.1 accuracy. I would be very happy to be accurate within 0.5 pH.

I see people saying you need to calibrate each time and store in a special solution. I don't think I want the extra task on brew day if I can avoid it. I also see that the probes do not last forever, apparently? So I wonder how far off do they get over time?

I have very lax requirements and I'm lazy. I just want an easy to read indication that I'm at or below 3. It's the cheap probe or the paper for me.

Does anyone have experience with the cheap probes? How bad does it get over time?

Thanks for anything you can share.

 

[VikeMan]

Cheap meters tend not to be very accurate. I've seen one meter that drifted so much that the owner thought it was normal for it to need calibration between each and every reading, i.e. a couple minutes after the last one.

Read this thread for an understanding of how meters work, how to figure out if a meter is good, and for some actual data on some meters that have been tested and pass muster. Some of them are not very expensive, but I doubt you're going to find a $10 meter worth owning. It's a long thread, but worth the read.

https://www.homebrewtalk.com/threads/ph-meter-calibration.302256/

 

[marc1]

Hi,

I got some pH strips to test that my Star San solution stays under 3. I find the strips a little difficult to read (is that orangish color 3 or 4?)

I won't be buying a very expensive meter but I might buy a cheaper one. I am curious if anyone has experience with these $10 Amazon "pen" models.

The cheap models claim 0.1 accuracy. I would be very happy to be accurate within 0.5 pH.

I see people saying you need to calibrate each time and store in a special solution. I don't think I want the extra task on brew day if I can avoid it. I also see that the probes do not last forever, apparently? So I wonder how far off do they get over time?

I have very lax requirements and I'm lazy. I just want an easy to read indication that I'm at or below 3. It's the cheap probe or the paper for me.

Does anyone have experience with the cheap probes? How bad does it get over time?

Thanks for anything you can share.

If you are using is for Star San and not wort, pH strips might be a great option. You would just need good ones so that you aren't trying to guess. Some have several indicators on them so that it is easier to differentiate.

 

[Upstate12866]

Thanks for the replies guys! The long post about calibration is gold. Looks like test strips might be the way for me based on what I'm reading. It can be really hard to tell 3 from 4 on my strips so some different ones are in order.

 

[danimal92sport]

Yes, I got a cheapie from Amazon a while back and it could not be trusted at all from reading to reading. Complete junk.

 

[crazyjake19]

I have a $12 cheap model from Amazon that I've had for a few years, as well as an Apera PH60 that I've had for the last 8-10 months. The cheapo is actually somewhat close but not as accurate or consistent as I would like it to be. It's often 0.2-0.3 higher than my Apera. I use that one for checking pH levels in soil or hydroponic nutrients where I want a rough idea but don't care if I'm a few tenths off in either direction.