For those who like to measure (pH). We salute you.

[duderonomy]

I am looking for a good working theory on what could be causing a consistent history of the following discrepancy between these two models of meters.

Pic is showing the issue. Ninety-nine percent of the time the new & improved meter is reporting a measurement that is a full 0.25 or more too high. Sometimes higher like 0.40 or more.

New meter has a second new probe. Same thing happened on the probe that came in the box.

The two old meters tend to agree. Old meters have attached, one very new probe; and one not new probe.

It's frustrating that I cannot get consensus among these meters when are all are calibrated with the same Hanna brand solution. The new one has a two-point calibration with Hanna 4 and Hanna 7. All meters will indicate 7 when in the calibration solution. But when they go into the solution that I need to measure, I get this anomaly.

Maybe once in 9-12 months had I ever seen them all agree. It was like seeing a ghost. haha.

I don't really have time to run an analysis of the pH reading across a range of EC points although that would be interesting to see. This pic is a reading of nearly RO water.

My tendency is to think the problem is the new meter.
After I check the calibration, I forget that I thought that until I compare meters again.

Homage to AC/DC's "For those about to rock!"

 

[duderonomy]

My plants have their opinion. Delivering a 6.4 to 6.5 solution, as measured by the old Hanna meters, appears to make the leaves flat with petioles angling upwards (the pray thing)... as I would expect. That was with RO. The new Hanna meter was showing 7.11 in this case.

I added some nutrients (what soil farmers call deadtrients). That raised the PPM to about 120 (500 scale). That brought the pH measurement of the GroLine HI9814 down closer to the other two meters. So they started to agree, again.

Maybe the Groline doesn't work well with RO or very low TDS solutions. I was thinking to ring Hanna but honestly that feels like it would be a big waste of time. They probably don't care. I'd like to hear if other people have any issue with the Hanna GroLine HI9814.

 

[Three Berries]

Are the meters all reading the same temperature?

 

[duderonomy]

Are the meters all reading the same temperature?

That's a great question.
My old Hanna meters are not the one's that show the temp.

 

[exploziv]

I don't think u supposed to expect good ph reading at that low ppm, tho. And if one of them is temp calibrated, the other one not.. that could be your answer. Try it at 20C, see if they agree.

 

[Three Berries]

Hanna has a pH probe cleaner. It's hydrochloric acid at 3%.

 

[Tomatoesonly]

I don't think u supposed to expect good ph reading at that low ppm, tho. And if one of them is temp calibrated, the other one not.. that could be your answer. Try it at 20C, see if they agree.

Yes, in this particular case that is exactly what I've read and was warned about. You can NOT pH R/O water or you'll burn out the probe.

 

[Three Berries]

My newer Apera pH20 went out of whack and can't calibrate. It's just over 6 months old, Apera said they will honor the warranty.

But they said the best storage solution if you don't buy the special KCl stuff is the 4.0 pH standard solution.

 

[Tomatoesonly]

My newer Apera pH20 went out of whack and can't calibrate. It's just over 6 months old, Apera said they will honor the warranty.

But they said the best storage solution if you don't buy the special KCl stuff is the 4.0 pH standard solution.

That's good to know. I've been using 7.0, I'll switch over to the 4.0 right away.

 

[Three Berries]

I had a Apera pH 20 that I let get dried out and it would not calibrate. So I got a new one. Then got some pH probe cleaner from Hanna and soaked the dried out Apera for about a week and it finally calibrated.

 

[smilley]

I gave up using ph pens years ago after my 4th one went out of wack. I just ignore ph now, I use tap water. Results seem just as good and it's much easier. I've taken to aerating the water for a day or so before mixing and watering with good results. Oh, I use PBP and pro-mix.

 

[Three Berries]

Apera told me my 6 mo old one was dirty. But they gave me a new one instead of just cleaning it so...

Probably the Humic acid stuff I use as it can really be clingy stuff if not totally mixed..

 

[AngrySquirrel]

I know this is a few weeks old but I thought I’d share my info for future readers. PH meters do go bad after like a year, according to several manufacturers. Always keep it in storage solution to keep it going for as long as possible.

Also, the calibration solution is very strong, so even if you stick it in and it reads 7.0, your nutrient solution isn’t as strong so it’s harder to get an accurate read on a bad meter. I would go with the newest meter you bought and make sure it’s calibrated of course. Aperas come with a certificate showing when it was made and calibrated by the factory so you know how new it is.

I have had both Apera and BlueLab. I’ve found the BlueLab to last longer than the Aperas but both are accurate when still new.

 

[Tomatoesonly]

I know this is a few weeks old but I thought I’d share my info for future readers. PH meters do go bad after like a year, according to several manufacturers. Always keep it in storage solution to keep it going for as long as possible.

Also, the calibration solution is very strong, so even if you stick it in and it reads 7.0, your nutrient solution isn’t as strong so it’s harder to get an accurate read on a bad meter. I would go with the newest meter you bought and make sure it’s calibrated of course. Aperas come with a certificate showing when it was made and calibrated by the factory so you know how new it is.

I have had both Apera and BlueLab. I’ve found the BlueLab to last longer than the Aperas but both are accurate when still new.

A person really really needs to have multiple ways of measuring pH, just to make sure everything agrees. I had a major snafu assuming my meter was all good till I happened to buy another one, and the numbers didn't agree at all.
So then I happened to have the old chemical drops in a vial type tester and used that to see which one was right. The newest one of course. The old one, a Milwaukee, would still 2 point calibrate but was wrong as hell on actual measurements of solution. I was able to restore the Milwaukee pretty close by storing the probe in the PROPER SOLUTION.
Funny how everything just exploded after I got my pH correct.

 

[negative37dBA]

I have always had issues with Hanna products. I have owned 4 different meters made by them they all were garbage. I made the switch to Blue Lab Guardians and never looked back. They have worked perfectly for 4 years of constant use.
Peace, negative.

 

[sublingual]

the storage solution seems to keep my meter in check. Doesn't seem to go out of calibration like it did on my previous one without keeping in the solution when stored.
Should be able to find how one can make their own if you don't want to pony up the cash.

 

[dramamine]

the storage solution seems to keep my meter in check. Doesn't seem to go out of calibration like it did on my previous one without keeping in the solution when stored.
Should be able to find how one can make their own if you don't want to pony up the cash.

It's easy and cheap to buy dry potassium chloride and make your own storage solution. Been using this for years and it works very well.

 

[sublingual]

It's easy and cheap to buy dry potassium chloride and make your own storage solution. Been using this for years and it works very well.

how much to put in a liter of water?

 

[dramamine]

how much to put in a liter of water?

200 grams KCL per 800ml of RO or distilled water. I keep it in the refrigerator, so no preservatives are needed.

 

[gmanwho]

i have had probably 30-40 meters over time. straight ph meters , ph ec temp combos. wands, ph dosers, handhelds and larger combos that stay on. hanna, milwaukee, blue lab, nutradip, china knock offs & sure i cant remember a few. trolmaster

They always drift, 2 brand new meters back to back calibrated in the same new solution will not read the same just a few minutes later.

I just calibrated 2 hanna groline combo meters with brand new probes. in the same brand new calibration solution & both probes sat together in the same ph ec calibration solution. what i learned is its not just hanna. its all of them. but i do love the hanna groline combo meters. i own 5 or 6 right now, every groline meter generation they made.

The Ph kci storage solution in the rubber caps is a must with the groline. I like the newer meters show a ph probe condition indicator on the screen.

The Longest stable running ph pen I’ve ever seen was a Milwaukee on my ph dosers. well over a year

As a grower once you start learning of all the variables that will change the ph in the medium on a constant basis, after you water/feed, that first ph measurement becomes less important to a degree. a 0.50 drift usually wont effect u to too much.


perfect ph becomes an addiction. i guess its cause you have a tool an can see a number on a screen . allows you to relate better. reading the plant an learning what changes will happen to that nutrient once its applied is far more important then being slightly off a ph measurement. The ph nutrient ion exchange rabbit hole is deep my friend!!

best of luck