PH meter Issues

[AlphaPhase]

So I have two of the exact same constant reading pH meters made by Hanna Instruments. They are great meters... But what I don't understand is that they both do not read the same pH.

Now, yes, they are both calibrated 100% to 7.01 and 4.01 pH solutions.

I calibrate them at the same time, they are always bang on 7 and 4 when I check every month or two to see if they need calibration, but they hold steady for a year most of the time.

But when I put both the meters in the same nutrient mix, they will give me different numbers.

One will read 5.8 and the other will read around 6.0-6.1

So then I put them in the calibration solution, in seconds they both read 7.0ph. (they are both brand new probes now, I bought a new one figuring one probe may be old because they always give me different numbers in the reservoir, but that is not the issue obviously).

Any one have ideas of why this is? I mean, . 2ph difference is pretty big. If I want 5.7 and it's 5.5, that's not what I want.

 

[DirtyMcCurdy]

What type of probe are they? Do they also read temp? If so, do they compensate for temp or not? The temp calibration could be different which would make them read different pH's. Or its just small differences in the probes/meters themselves. Although you would think Hanna would have a better QA program then that.

 

[BobCajun]

What type of probe are they? Do they also read temp? If so, do they compensate for temp or not? The temp calibration could be different which would make them read different pH's. Or its just small differences in the probes/meters themselves. Although you would think Hanna would have a better QA program then that.

Did you try pulling out some more of the wick and cutting the old end off? Maybe it got contaminated with something. Also do you store them with storage solution?

 

[AlphaPhase]

What type of probe are they? Do they also read temp? If so, do they compensate for temp or not? The temp calibration could be different which would make them read different pH's. Or its just small differences in the probes/meters themselves. Although you would think Hanna would have a better QA program then that.

I use these meters and probes. I'm not sure if they compensate for different Temps. Hmm. There isn't a way to calibrate the Temps anyway. That does make sense that maybe there's just small differences in the probes possibly. I did get them to read only .1-.2 off from each other with some tinkering, but they still won't read the same. I definitely agree, I would think Hanna would have their meters reading the same, especially when they are 160$ each

 

[adower]

Drop those and get a blue lab guardian.

 

[blackforest]

When I had ph pen issues, I bought the liquid GH ph test kit for my backup. I always use it now because it's simple and it's consistent. After awhile you can notice the slightest color change and practically know the exact ph just by the color. Easy to know if your pen is off that way imo. 8 bucks, lasts for a very long time.

http://www.ebay.com/itm/like/121686995735?ul_noapp=true&chn=ps&lpid=82

 

[Aeroknow]

Nothing wrong with those grocheck combo meters. @AlphaPhase knows I have a bunch of them,
I still perfer that meter over newer ones, because you calibrate it via trimmer screws. Newer meters piss me off because it's all electronically now.

AP, i'll check you out later bro.
Try getting 4 of them at the same grow location to read identical
Usually 1 of them will end up .1 off from the others. No biggie!
Like i said, see you later dude

 

[hotrodharley]

So I have two of the exact same constant reading pH meters made by Hanna Instruments. They are great meters... But what I don't understand is that they both do not read the same pH.

Now, yes, they are both calibrated 100% to 7.01 and 4.01 pH solutions.

I calibrate them at the same time, they are always bang on 7 and 4 when I check every month or two to see if they need calibration, but they hold steady for a year most of the time.

But when I put both the meters in the same nutrient mix, they will give me different numbers.

One will read 5.8 and the other will read around 6.0-6.1

So then I put them in the calibration solution, in seconds they both read 7.0ph. (they are both brand new probes now, I bought a new one figuring one probe may be old because they always give me different numbers in the reservoir, but that is not the issue obviously).

Any one have ideas of why this is? I mean, . 2ph difference is pretty big. If I want 5.7 and it's 5.5, that's not what I want.

Forgive me but have you contacted Hanna Tech Support?

 

[Aeroknow]

Btw, it is most likely a temperature issue.
AP, if you were to plug both meters into the same location/same room, put all electrodes into the same solution, and let em both chill in that solution for a bit, i bet they will be more identical

 

[AlphaPhase]

Drop those and get a blue lab guardian.

That does look like a nice meter, maybe next time I get another one I'll try that out.

Nothing wrong with those grocheck combo meters. @AlphaPhase knows I have a bunch of them,
I still perfer that meter over newer ones, because you calibrate it via trimmer screws. Newer meters piss me off because it's all electronically now.

AP, i'll check you out later bro.
Try getting 4 of them at the same grow location to read identical
Usually 1 of them will end up .1 off from the others. No biggie!
Like i said, see you later dude

Right on, I did have them in the same room, they'll both read exact same in the solutions, but then when I put them in the res one will read .1 different, I got it closer than .2 though so that's a huge plus. .2 off was really irritating me lol

I've had nothing but problems with hanna meters, I had 2 different model hanna's and they would also never read the same ph, Throw them both in the garbage because even after they are calibrated neither of them are reading the correct ph. I bought a Anaheim Scientific meter, calibrated all 3 meters and the Anaheim reads a different ph than either of the hanna's and it is always consistent. It also only takes a couple seconds to read the ph where the hanna's seem to take a minute or two. This is the one I bought:
http://www.amazon.com/gp/product/B00CMFVXMA?keywords=ph meter scientific&qid=1446496631&ref_=sr_1_1&sr=8-1

Does this brand have a constant reading meter I can mount to the wall? I mean, I really like the ones I have because they hold the calibration for a long time and last for years, but I just wish I could get them to read the exact same

Forgive me but have you contacted Hanna Tech Support?

I haven't contacted them yet, I was thinking about it but I figured they would just tell me to do the things I've already tried