Apera pH reading counts up

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MBPooldiy

MBPooldiy

Well-known member
Jun 14, 2022
60
Phoenix
Hi Apera users,
I have been loving my PH60 for about a year and a half for getting quick and accurate pH readings. However I've noticed that over time it has become more difficult to get a stable pH reading and as I've begun ramping up for the new season here in Phoenix it I'm finding it difficult to trust the reading at all. At this point if I note the reading the first time the stabilizer indicator remains on steadily, then swirl the meter around, wait for re-stabilization again and repeat this a few times, I can get the meter to read easily .5ppm higher than the original reading. I just recalibrated it and changed to very fresh kcl fluid last week but doesn't seem to have improved. Has anyone else seen this and is it an indication that the device is degrading or needs some part replaced?
 
I have mine set to HOLD once it stabilize. Then I must turn it off, then on again to take a 2nd reading.
When I remove the cap which has the KCL liquid in it, I spray the probe with pool water to rinse the KCL from the bulb. Then I place it in a tub filled with the same pool sample water. I swirl it around then let it stand until it stabilizes then go into HOLD mode. I then turn it off, shake off the liquid, turn it on and swirl again in the tub and let it stand. When it reaches stabilization and goes into HOLD that is my reading. The difference between the 1st and 2nd reading can be several 100ths i.e. 7.64 to 7.71.
I have never had it increase by 0.5 - meaning 7.2 to 7.7. If that is was the case then I would recalibrate. I have found the steps for calibration can be a little misleading. I read them over and over as I go through each of the calibration points from low to high.

Not sure I answered your question but it does seem odd to increase by 0.5
 
Your pool water is still quite cold. We had that discussion the other day, where the OP observed effects of similar order. In the end, the OP from that thread called Apera and asked them:

engrav said:
So called 'em. Said if temp water and temp probe grossly different strange things happen.
Click to expand...

I don't trust my pH-meter reading until the temperature shown on the meter is within about 0.5°C of the temperature shown by my pool thermometer. Whether the smiley smiles earlier or not - the smiley doesn't know if the internal temperature probe is already thermalized to the water temperature.

I always make sure that it's my meter that adjusts to the water temperature, and not the water sample that adjusts to the meter temperature.

When probe and water temperature are similar (in summer) then I just stick the meter straight into the pool, within about 30 sec I usually get a reliable reading.

In winter, when the water is much colder than the pool water, it can take up to 2 minutes for the probe to cool down to the water temperature. I then take a larger sample in an ice cream tub and hook the meter with its clip over the rim of the tub and let it sit outside. Then I go inside, run my FC test, and by the time I'm done with that and put my test kit back into the cupboard, the pH-reading has stopped drifting.
 
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Thanks so much--it's the answer that explains it. I had been trying to stick the meter directly into my pool as I do in the summer. So I put some pool water into my measuring bucket and let it sit. I then noticed that the temperature on the probe was counting down as the meter reading counted up. After a couple of minutes everything stabilized and the reading was more as I would expect, including the temperature indicated on the Apera was same as the thermometer in my pool. I didn't realize that the smiley indicator was not smart enough to sense that the temperature had not stabilized. I will be interested in checking this out in the summer as well. In July, my pool water is typically about 10 deg warmer than the house temperature where the meter is stored. In the winter it's about 10 degrees in the opposite direction (currently 58 deg water temperature).
 
Yes, will be interesting how it behaves in summer. In my case the pool is not heated, so pool and house are not that dissimilar in summer.

As the probe gets older, it will also behave more sluggish, so that effect could be overlaid.
 
mgtfp said:
Your pool water is still quite cold. We had that discussion the other day, where the OP observed effects of similar order. In the end, the OP from that thread called Apera and asked them:



I don't trust my pH-meter reading until the temperature shown on the meter is within about 0.5°C of the temperature shown by my pool thermometer. Whether the smiley smiles earlier or not - the smiley doesn't know if the internal temperature probe is already thermalized to the water temperature.

I always make sure that it's my meter that adjusts to the water temperature, and not the water sample that adjusts to the meter temperature.

When probe and water temperature are similar (in summer) then I just stick the meter straight into the pool, within about 30 sec I usually get a reliable reading.

In winter, when the water is much colder than the pool water, it can take up to 2 minutes for the probe to cool down to the water temperature. I then take a larger sample in an ice cream tub and hook the meter with its clip over the rim of the tub and let it sit outside. Then I go inside, run my FC test, and by the time I'm done with that and put my test kit back into the cupboard, the pH-reading has stopped drifting.
Click to expand...
Where do you buy your calibration solutions from? Do you renew every six months?
 
xDom said:
Where do you buy your calibration solutions from? Do you renew every six months?
Click to expand...

I usually order from instrumentchoice or directly from Hanna.

My 3M KCl storage solution (Sera Care) I buy from petsuppliesempire.com.au. I can't recommend enough to always store the probe in storage solution.

I relaxed a bit with the 6 months after comparing old bottles with new bottles. pH 4 is quite stable, pH 10 is less stable (more susceptible to CO2 absorption after bottles have been opened).
 
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mgtfp said:
I usually order from instrumentchoice or directly from Hanna.

My 3M KCl storage solution (Sera Care) I buy from petsuppliesempire.com.au. I can't recommend enough to always store the probe in storage solution.

I relaxed a bit with the 6 months after comparing old bottles with new bottles. pH 4 is quite stable, pH 10 is less stable (more susceptible to CO2 absorption after bottles have been opened).
Click to expand...
Have you noticed any difference in readings in where you retrieve your sample? My first sample was at surface level and the second was at arm's length in the water. The second seemed to be where I was expecting the value to be.
Does this make sense?
 
MBPooldiy said:
Hi Apera users,
I have been loving my PH60 for about a year and a half for getting quick and accurate pH readings. However I've noticed that over time it has become more difficult to get a stable pH reading and as I've begun ramping up for the new season here in Phoenix it I'm finding it difficult to trust the reading at all. At this point if I note the reading the first time the stabilizer indicator remains on steadily, then swirl the meter around, wait for re-stabilization again and repeat this a few times, I can get the meter to read easily .5ppm higher than the original reading. I just recalibrated it and changed to very fresh kcl fluid last week but doesn't seem to have improved. Has anyone else seen this and is it an indication that the device is degrading or needs some part replaced?
Click to expand...
The sensor tip is replaceable. Should be changed yearly.
 
xDom said:
Have you noticed any difference in readings in where you retrieve your sample? My first sample was at surface level and the second was at arm's length in the water. The second seemed to be where I was expecting the value to be.
Does this make sense?
Click to expand...
I have never made a direct 1:1 comparison, but surface water is generally more affected by rainfall, warming up of surface layers, etc. So, taking a sample from arm's length makes always sense. But in well mixed pool water with the pump running the differences shouldn't be huge.

pH I usually test by sticking my meter straight into the pool, and the results always made sense.
 

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Storing them wet, in the correct storage solution is a must. Over the years I haven’t had much luck with pH meters even when stored wet and now always calibrate before use, although I haven’t used the Apera. But I did have a pH controller for a few years where the probe is always in the solution and it held its calibration quite well.

It’s probably a good time (pre or post season) to clean the probe with a cleaning solution. Hanna explain what can happen on the bottom of their general cleaning fluid page.

hannainst.com.au

HI7061M General Purpose Cleaning Solution (230 mL) - Hanna Instruments Australia

HI7061M is a general purpose cleaning solution that can be used for a variety of applications. Electrodes can become dirty from use and will produce inaccurate results even as they read correctly in a pH buffer. Hanna’s cleaning solutions eliminate impurities and residues that are left on...
hannainst.com.au hannainst.com.au
 
I have to say that my Apera holds its calibration nicely, didn't have to recalibrate in months. Always stored in KCl.

I use a Hanna pH 8.2 buffer to check the calibration. Like that I only need one test to verify that the meter is reliable in the pH-range around 8.0 that I'm interested in.
 
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mgtfp said:
I have to say that my Apera holds its calibration nicely, didn't have to recalibrate in months. Always stored in KCl.

I use a Hanna pH 8.2 buffer to check the calibration. Like that I only need one test to verify that the meter is reliable in the pH-range around 8.0 that I'm interested in.
Click to expand...
I can't find the post that this relates to but I know you said you let your pH run higher in winter.. to what? 8.2?
 
mgtfp said:
Not quite as high. It's usually still below 8.1 when I bring it down again, but only to about 7.9
Click to expand...
So to counter the temperature decrease do you rely solely on the the pH increase to keep CSI happy?
Do you adjust TA at all in winter?
I think I remember you saying you don’t add TA increaser at all ( yet your TA is at 80). ?
 
xDom said:
So to counter the temperature decrease do you rely solely on the the pH increase to keep CSI happy?
Do you adjust TA at all in winter?
I think I remember you saying you don’t add TA increaser at all ( yet your TA is at 80). ?
Click to expand...

Pretty much. Haven't added baking soda in years. Depending on rain dilution/overflow in winter I have to increase CH from time to time (counted more in years than months). TA hovers around 80.
 
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