Reccomended PH Probe

[Richardod]

Is there such a thing ? I have a MIlwakee Ph600 and it is useless it fluctuates all the time and I just don't trust it
I don't mind spending out on a decent one ,be nice to hear of anyone who has a trustworthy one to reccomend.

I tested the PH in my tank using a JBL liquid drop test and it shows at least a 1PH drop according to their Colour chart from Gass on to Gass off when using the Milwakee PH600 and it barely shows a 0.2 drop .
I would like to get a decent PH profile for my tank but not really sure how to do it without a decent probe.

 

[blairgerman]

Hi, not sure if this is helpful but I find that these probes never last long when not stored in ph probe storage solution. I think the hanna ones have replaceable probe sensors. For me, even when properly used, ph probes tend to go out of spec in 6 months to a year max. I keep some 4,6,10 reference solution around to check them. I think the one you have indicates to use solution in the cup cap thing... likely you're already doing this, but just letting you know in case that might be part of your issue.

 

[ian_m]

I have a MIlwakee Ph600 and it is useless it fluctuates all the time and I just don't trust it

Could be an electrical field issue as pH probes are very sensitive to small electric "leaks" from electrical in tank equipment.
Unplug all your tank electrics from the mains socket and try pH readings again and see if there is any difference in reading.

 

[dw1305]

Hi all,

Is there such a thing ? I have a MIlwakee Ph600 and it is useless it fluctuates all the time and I just don't trust it
I don't mind spending out on a decent one ,be nice to hear of anyone who has a trustworthy one to reccomend.

Approximately how much is "spending out", they get pretty pricey, pretty quickly. If you want an a <"reasonably accurate one"> you are into the £ hundreds and if I was going to buy one (rather than <"just using the ones at work">) <"I'd get a solid state ISFET meter">.

For me, even when properly used, ph probes tend to go out of spec in 6 months to a year max. I keep some 4,6,10 reference solution around to check them. I think the one you have indicates to use solution in the cup cap thing... likely you're already doing this, but just letting you know in case that might be part of your issue.

There are also <"ongoing maintenance costs">, as @blairgerman mentions.

I think the hanna ones

Hanna would probably be the manufacturer I'd start with.

I tested the PH in my tank using a JBL liquid drop test and it shows at least a 1PH drop according to their Colour chart from Gass on to Gass off when using the Milwakee PH600 and it barely shows a 0.2 drop .

I honestly wouldn't make decisions about fish welfare based on a pH meter reading, from any meter (other than an ISFET one). The only provisos to that are:

• <"if it was a lab. one">,
• had received frequent maintenance,
• I had access to three meters and
• that they all read the same value.

I'm not a CO2 user, but if I was I'd be happier with multiple drop checkers, because bromothymol blue is <"a reliable narrow range pH indicator"> and I can make up my own 4dKH solution.

cheers Darrel

 

[MichaelJ]

Hanna would probably be the manufacturer I'd start with.

I was thinking of getting this one from Hanna Instruments for a while.

Notice that the set of calibration fluids costs almost as much as the probe.

Darrel, I wonder if you know what the deal is with the frequent calibration of pH probes, why is it that they cant just be calibrated once from the factory? I wonder what causes them to drift off from the calibration values?

With my Hanna TDS DIST1 I "calibrate" it occasionally but when I dip it in the calibration fluid before pressing the Calibrate button its usually just a couple off ppm's (+/- 1-2) off from the 1382 ppm. of the calibration fluid - which sort of make the calibration unnecessary.

Cheers,
Michael

 

[dw1305]

Hi all,

I wonder if you know what the deal is with the frequent calibration of pH probes

Unfortunately they need calibrating every time you switch them on, and you are even meant to re calibrate them every so often when you are doing a continuous long run of samples.

You really need two point calibration (pH 7 & pH 4 or pH 10) as well, dependent on what you think the pH of your sample solution may be. You can <"add a neutral salt to your sample"> and that stabilises how long the meter drifts for before stabilising, but that drift period could be ~10 minutes in a low conductivity situation, even with an expensive (~$1000) meter.

With my Hanna TDS DIST1 I "calibrate" it occasionally but when I dip it in calibration fluid before pressing the Calibrate button it usually just a couple off ppm's (+/- 1-2) off from the 1382 ppm.

Yes, and that is one reason why I like conductivity (TDS) as measurement, the meters are pretty much "plug and play" and you can go for weeks at a time without re calibrating them, without the calibration drifting. You can also make up your <"own calibration solutions"> easily.

We have a good test for the differences between ease of pH and conductivity measurement, we have a small spring fed water course on campus (<"Corston Brook">), that runs through a wood into a lake.

<"The whole, small catchment"> is on <"190 - 210 million"> year old <"Lias limestone and clays">,

The underlying geology is mapped as interbedded Langport Member and Blue Lias Formation mudstone and limestone (BGS 2012).

which means that the water in the brook is always fully saturated with Ca++ and 2HCO3- ions and the pH will always be ~pH 8, via the pH ~ conductivity ~atmospheric CO2 equilibrium.

Conductivity can vary dependent on how much rainfall we've had, but is always in the range of <"300 - 750 microS"> and dissolved oxygen somewhere around 100%, when we take out readings (with the students always in winter or spring).

When the students take their readings ~99% of the conductivity and DO readings will be very, very similar, but the pH readings will be absolutely anything from pH6 to pH9, although most will be somewhere around pH8. I know it isn't the meters, they were all calibrated before they left the lab. and then re-calibrated in the field, so it is "user error", but it disproportionably effects pH meters.

cheers Darrel

 

[MichaelJ]

When the students take their readings ~99% of the conductivity and DO readings will be very, very similar, but the pH readings will be absolutely anything from pH6 to pH9, although most will be somewhere around pH8. I know it isn't the meters, they were all calibrated before they left the lab. and then re-calibrated in the field, so it is "user error", but it disproportionably effects pH meters.

cheers Darrel

That's a very interesting lesson for sure. I wonder what sort of "user error" that would be? Like not holding the meter in the sample long enough or too long, contaminating the probe etc.

Unfortunately they need calibrating every time you switch them on

Thats the bit I do not understand. Probably because I do not know how an electronic pH probe works in the first place.

Cheers,
Michael

 

[Wookii]

I think it depends on the individual pH probe as well (the individual sample, not just the individual model). My Hanna Halo probe (that I managed to smash recently! 🤬🤬) would drift no more than about 0.04pH every 3-4 months of intermittent use. I'd open up a couple of calibration solution sachets to calibrate, and get only a 0.0.1-0.02 pH change and wonder why I'd bothered. Conversely the new Hanna titanium one I bought to replace it (though half the price which might explain it) seems to drift 0.02pH in less than an hour!

 

[John q]

Thats the bit I do not understand.

From what I can gather the electrodes and inner solutions deteriorate over time, so basically they constantly drift, hence they need constant calibration to ensure accuracy.

It's all a bit above my head mate... here's the explanation by Hanna.

"pH meter calibration is a necessary step of using a pH meter because of how the electrode changes over time. Your pH electrode is designed to measure pH based off of slope and offset (the Nernst Equation).

However because of aging and use, the electrode's performance will stray from the theoretical slope and offset over time. Regularly calibrating your pH meter will adjust your electrode based off any changes that may have occurred and ensures that your readings are accurate and repeatable."

 

[dw1305]

Hi all,

Probably because I do not know how an electronic pH probe works in the first place.

They work by swapping an internal potassium (K+) ion for an external proton (H+ ion) in the water. Because <"pH is a measure"> of the relative ratio of H+ and OH- ions (I'm going to ignore the <"log 10 scale, the hydronium ion and the self-ionization of water">) then the more potassium ions you exchange (from the internal reservoir of KCl (K+ and Cl-)) the more acid the solution is, and the lower the pH. You measure the quantity of K+ ions by measuring their electrical conductivity as they flow between the probe and reference electrode.

Your pH electrode is designed to measure pH based off of slope and offset (the Nernst Equation)

Thanks @John q I should have done that bit. <"Nernst Equation">. There are really useful pH theory guides at: <"pH Theory Guide"> & <"https://www.pragolab.cz/files/aktuality/2015-03/pH-Measurement-Handbook.pdf">.

I wonder what sort of "user error" that would be? Like not holding the meter in the sample long enough or too long, contaminating the probe etc.

Not waiting long enough would be my guess, or not going through the buffering process properly. One problem is that the buffers are very "salty", so as the internal reservoir of potassium ions declines drift is not as obvious in the buffer as it is in the water sample, even if its hard water. The electrodes don't fail catastrophically they just become more and more difficult to calibrate as the internal reservoir of K+ ions is exhausted. The calibration is meant to take into account these changes, but only within certain tolerances.

The reservations I have are the same ones I have for <"nitrate (NO3-) testing">, they are basically <"issues of probability">. It isn't that all of the values are all wrong, it is just you don't actually know which values are "right" ones.

Nitrate (NO3-) and pH are two of the values that I would really like to know, which is why I've used proxies (<"Duckweed and snail shell indices">) to estimate them. It isn't anything like as good as being able to measure them accurately, but a <"ball-park figure"> is probably better than measuring them inaccurately, if that makes sense?

cheers Darrel

 

[MichaelJ]

I think it depends on the individual pH probe as well (the individual sample, not just the individual model). My Hanna Halo probe (that I managed to smash recently! 🤬🤬) would drift no more than about 0.04pH every 3-4 months of intermittent use. I'd open up a couple of calibration solution sachets to calibrate, and get only a 0.0.1-0.02 pH change and wonder why I'd bothered. Conversely the new Hanna titanium one I bought to replace it (though half the price which might explain it) seems to drift 0.02pH in less than an hour!

From what I can gather the electrodes and inner solutions deteriorate over time, so basically they constantly drift, hence they need constant calibration to ensure accuracy.

It's all a bit above my head mate... here's the explanation by Hanna.

"pH meter calibration is a necessary step of using a pH meter because of how the electrode changes over time. Your pH electrode is designed to measure pH based off of slope and offset (the Nernst Equation).

However because of aging and use, the electrode's performance will stray from the theoretical slope and offset over time. Regularly calibrating your pH meter will adjust your electrode based off any changes that may have occurred and ensures that your readings are accurate and repeatable."

hey work by swapping an internal potassium (K+) ion for an external proton (H+ ion) in the water. Because <"pH is a measure"> of the relative ratio of H+ and OH- ions (I'm going to ignore the <"log 10 scale, the hydronium ion and the self-ionization of water">) then the more potassium ions you exchange (from the internal reservoir of KCl (K+ and Cl-)) the more acid the solution is, and the lower the pH. You measure the quantity of K+ ions by measuring their electrical conductivity as they flow between the probe and reference electrode.

Hi all, I think I understand the basic chemistry, what I could not wrap my head around was the frequent calibration. If the Hanna Halo that @Wookii used only needed calibration every 3-4 months then that would be a different technology or way of measuring vs. the ones your using in the lab that needs calibration every time its switched on (which I figure may be more precise for lab work) , correct?

Cheers,
Michael

 

[Richardod]

Could be an electrical field issue as pH probes are very sensitive to small electric "leaks" from electrical in tank equipment.
Unplug all your tank electrics from the mains socket and try pH readings again and see if there is any difference in reading.

Thanks for your suggestion - I tried that still the same problem

 

[Richardod]

Thanks @dw1305 I had absolutley no idea a decent one was so expensive coupled with the required maintenance its too much trouble.
I think I will just rely on a couple of drop checkers .
I would have liked to have done a PH profile on my tank but not if it's going to cause all the hassle of maintaining an expensive probe.

 

[dw1305]

Hi all,

what I could not wrap my head around was the frequent calibration. If the Hanna Halo that @Wookii used only needed calibration every 3-4 months then that would be a different technology or way of measuring vs. the ones your using in the lab that needs calibration every time its switched on (which I figure may be more precise for lab work) , correct?

A bit of both I'd guess, the electrode (<"ISFET etc">) type is probably going to make most difference. Problems are most likely to occur in the pH 6.5 to pH 7.5 range (around neutral), particularly in solution with low electrical conductivity.

...... An ISFET electrode sensitive to H+ concentration can be used as a conventional glass electrode to measure the pH of a solution. However, it also requires a reference electrode to operate. If the reference electrode used in contact with the solution is of the AgCl or Hg2Cl2 (calomel) classical type, it will suffer the same limitations as conventional pH electrodes (junction potential, KCl leak, and glycerol leak in case of gel electrode). A conventional reference electrode can also be bulky and fragile......

........ For this reason, since more than 20 years many research efforts have been dedicated to on-chip embedded tiny reference field effect transistors (REFET). Their functioning principle, or operating mode, can vary, depending on the electrode producers and are often proprietary and protected by patents. Semi-conductor modified surfaces required for REFET are also not always in thermodynamical equilibrium with the test solution and can be sensitive to aggressive or interfering dissolved species or not well characterized aging phenomena. This is not a real problem if the electrode can be frequently re-calibrated at regular time interval and is easily maintained during its service life. However, this may be an issue if the electrode has to remain immersed on-line for prolonged period of time, or is inaccessible for particular constrains related to the nature of the measurements itself....

As long as people recognise that you can't just dip the meter in the tank and get an accurate reading, that the electrodes must be stored in the appropriate storage solution, the pH scale isn't linear etc. it reduces the risks of things going "wrong".

This video is the best one I've found. The pH bit is from 7:37, but it is all worth watching. I'll add in @jaypeecee as he is better equipped to pass comment than I am.



cheers Darrel

 

[zozo]

If the cause is electrical interference from whatever source, then try grounding the tank water with a titanium grounding probe. Then any electric charge from the water will flow out this way (path of least resistance) and will not flow over the Ph probe and interfere. The probe is connected to the power grid with a positive and a negative lead and will also ground the tank water.

Some Hanna Ph probes come from the factory with an extra grounding pen installed. Such as the one in the picture below.

Or put the Ph probe outside the aquarium with a T and IP68 cable gland inline in the filter hose that returns to the tank. Something like this already works a charm. But you can buy factory-made inline probes as well.

For the rest, good idea grounding an aquarium? It has proponents and opponents...

What Is an Aquarium Drip Loop?

Maybe you've been told to have a drip loop when you set up your aquarium. Do you really need one, and what is it anyway?

www.thesprucepets.com

Pick a side...

A nice analogy is: The fish in the ungrounded aquarium is like a bird sitting on an electrical (ungrounded) power line. (The bird will get zapped if would go sit on a grounded power line)