Recommendation for PH tester

[AUSpool]

And for everyone using a cheap pH meter the second decimal point is only used to round up or down. Your kidding yourself if you think you can get to +/_ 0.01 pH unit.

That was a bit harsh of me. I think your likely to be close to +/-0.02 with everything else being up to standard so to speak. But for pool care that second place is good to round up or down as needed and have confidence in the result. I recall a lab prac a few years back where about 10 groups of 3 performing the same test, all using the same calibrated lab grade equipment and starting from the same master standard, all got a range of results. The results were close but some just outside of the manufacturers reported margin for error.

Traditionally TFP has avoided discussions about, and the use of digital meters for various reasons. Certainty of results for advice and sending the wrong message to those that are new to pools. But times change, TFtestkits and Taylor both sell digital meters, and I think we should be able to discuss the proper use of them. Sure, there may be occasions where those new to pools get the wrong message but we should deal with that as required and those that are new to pools will eventually be exposed to digital meters. You cant keep their little hands out of the cookie jar for ever.

 

[mgtfp]

Try a different drop test comparator, they’re cheep, last forever and don’t need calibrating. Look through it with a white background behind. Manipulate the colour with the acid demand agent.

I’ve never been a fan of colourmetric tests and never able to use the Taylor pH comparator. It compares a opaque coloured solution to a solid colour on a card. It was just to hard for me to master. I switched to an old Blue Devil pH comparator that came with the old house and it was easier to use. This comparator has opaque windows that are similar to the test solution and is easier to match. I still use the Taylor reagent because its better but since my comparator uses less test solution I use one less drop.

My Blue Devil kit came today. I think that does the trick, the translucent scale really helps.

Another thing is the number of drops. The Taylor test is designed to work with 5 drops of R-0004 in a 44ml sample. Some forum members report that 4 drops make it easier to read. I have never used the actual Taylor kit, but the Australian Clear Choice Labs kit. The CCL instructions say to add 2 drops of their reagent to a 10ml sample - that results in a really intense colour that I was always struggling with. According to CCL's compatibility chart, their phenol red reagent is fully compatible with Taylor's R-0004 (incl. drop size). That means that the CCL test according to their instructions is equivalent to running a Taylor test (44ml sample) with 9 drops - that could well explain why I was always struggling with the test. Maybe CCL deliberately wants the colours to be more intense to resemble the less translucent printed colour scale?

Using the Blue Devil comparator (with a very translucent colour scale and a sample volume of 35ml) with 4 drops of reagent (equivalent to 5 drops in Taylor's 44ml) works already much better for me, and using 3 drops (equivalent to 4 drops in 44ml) seems to be the winner - I can finally read a phenol red pH-test

Thanks @AUSpool, that was great advice and really helped!

 

[MostlyCanuck]

To those of you who have been using these for a while now, what's the shelf life / longevity of both the storage and calibration solutions? I think I read they're only good for a few weeks, and that the solutions shouldnt be recycled (single use). Is that right? Looking at options on Amazon (in Canada) these solutions seem very pricey if they're to be replaced that often...

 

[DanF]

For the storage (KCl) solution, I fill it up to the "Fill" line and replace when the level gets too low to cover the probe. Each time the tester is used a little KCl dissipates/drops off due to distilled water rinsing. I purchased it on Amazon in January 2021 and it had an expiration of Jan 2022.

The calibration solution can be reused, per conversation with Apera. I calibrate once a week and refill the solution every 8-10 tests or so.

 

[MostlyCanuck]

For the storage (KCl) solution, I fill it up to the "Fill" line and replace when the level gets too low to cover the probe. Each time the tester is used a little KCl dissipates/drops off due to distilled water rinsing. I purchased it on Amazon in January 2021 and it had an expiration of Jan 2022.

The calibration solution can be reused, per conversation with Apera. I calibrate once a week and refill the solution every 8-10 tests or so.

thank you, this is quite reassuring. do you think it matters if the storage / calibration solutions are Apera's for use with their testers? I would imagine there's nothing proprietary about these and brand doesnt really matter, does it?

 

[DanF]

thank you, this is quite reassuring. do you think it matters if the storage / calibration solutions are Apera's for use with their testers? I would imagine there's nothing proprietary about these and brand doesnt really matter, does it?

I am not 100% sure, but I went ahead and purchased Apera's just to be safe. With the KCl, I was told on this forum to be sure that it is the "3M" (3 mole I believe) variety.
Here's what I have

 

[AUSpool]

I would not reuse calibration solutions. No double dipping. It will lead to cross contamination of your solutions and render your future calibrations invalid. You don’t need a lot of solution to calibrate, just enough to cover the tip.

Brand doesn’t matter much but but I would have more confidence in a Hanna solution then a no name ebay solution. It is important to get solutions that match your meter, particularly if your meter calibrates to a set point. Ie. Get a 7.01 solution for meter that auto calibrates to 7.01, don’t go for 7.00 or 6.98 solution.

For pool use it would be best practice to calibrate pH at 7.00 and 10.00. And calibration needs to be done at the correct temperature, normally it’s 25degC or 77degF.

Solutions should last a year if used properly.

Calibration could be monthly or more. After you calibrate a new meter for the second and third time you will get an idea of how often it will need calibration.

I would not have thought that cleaning was important but according to the folks at Hanna it is.

 

[setsailsoon]

To those of you who have been using these for a while now, what's the shelf life / longevity of both the storage and calibration solutions? I think I read they're only good for a few weeks, and that the solutions shouldnt be recycled (single use). Is that right? Looking at options on Amazon (in Canada) these solutions seem very pricey if they're to be replaced that often...

That was not my experience. I would pour out the small amount in a separate container and use it for about a week or two. A bottle of calibration fluid lasted me about a year. Same for storage solution.