Pocket pH tester update
- Thread starter setsailsoon
- Start date
- May 23, 2015
- 24,506
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Are you sure about that?
Who me?
Yes. Absolutely. pH is a scale that is chosen to be what it is because water is the most readily abundant solvent on the planet. There are other fundamental assumptions that go into the definition of pH that makes the scale be 0 to 14. For example, the activity of pure water is chosen to be 1. It's not a fundamental quantity that someone measured to be 1, rather it is defined to be 1. Why? Makes the math a lot simpler.
So yes, solutions can have pH values outside what we, human being nerds, define as "standard"....
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While true, the world usually runs on 0-14. No Pocket pH tester needs to go outside that, nor would one be accurate for long testing those extremes.
- May 23, 2015
- 24,506
- Pool Size
- 16000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Agreed. Stick one of those pocket testers in 27M NaOH (highest concentration possible at room temperature) and I doubt very much it would last more than a minute or two....
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- Sep 23, 2015
- 1,598
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V25
I never really thought about it, just copied from the instructions. Why not 0 - 14 instead of 2 - 16? must be an application for it I guess.
http://ep.yimg.com/ty/cdn/yhst-83212413117752/Mil-Manual-PH55-56.pdf
Fascinating, I never knew pH could go above or below the 0 - 14 either. There's always somthing new to learn or more to the story. But my point really is about choice, for ~$10 more you can get one that's twice as accurate. It pays to read the fine print prior to purchase.
http://ep.yimg.com/ty/cdn/yhst-83212413117752/Mil-Manual-PH55-56.pdf
Fascinating, I never knew pH could go above or below the 0 - 14 either. There's always somthing new to learn or more to the story. But my point really is about choice, for ~$10 more you can get one that's twice as accurate. It pays to read the fine print prior to purchase.
- Oct 25, 2015
- 5,213
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Folks,
My original Dr. Tester started to get difficult to calibrate and the readings seemed to wander around after I accidentally let the probe dry out so I went on a search for a replacement. I found a new one that has an incredible auto calibrate feature dirt cheap on Amazon. Less than $12! I thought it must be junk but I'd test it anyway. So I started using it March 4 and amazingly it's still going strong! I'm pretty skeptical due to the price so I'm testing frequently and using a blind comparison... you may recall I'm color blind in the red shades that read 7.8+ on the Taylor test. So I have my wife read the Taylor and I check with my meter. All readings so far are within .05 ph units calibrating only once per week. I also keep the probe in phosphate buffer storage solution as recommended by all the manufacturers of ph probes. You can find the unit I bought by searching Amazon or Google for "
Auto Calibration Mini Digital Pocket Pen Type PH Meter Multimeter Tester Hydro". There are also other brands at the bottom of the page. I have no idea which one is best.
Incidentally, if you are like me and need something other than the Taylor red shade color test for ph the auto calibrate meters are much easier to use... no more fiddling with the tiny adjustment screw. You just put the meter in the calibration fluid then press the calibrate button. The meter electronics do the rest. Just be sure you know what calibration fluids your meter uses. Some have an ability to calibrate with two different fluids like the one I have so you can calibrate above and below the typical reading you see. Hanna has a good selection of calibration fluids at a pretty good price and online gardening supply stores have more limited ph level calibration fluids at great prices.
I'll update later when I have more data and I hope these posts are helpful.
Chris
My original Dr. Tester started to get difficult to calibrate and the readings seemed to wander around after I accidentally let the probe dry out so I went on a search for a replacement. I found a new one that has an incredible auto calibrate feature dirt cheap on Amazon. Less than $12! I thought it must be junk but I'd test it anyway. So I started using it March 4 and amazingly it's still going strong! I'm pretty skeptical due to the price so I'm testing frequently and using a blind comparison... you may recall I'm color blind in the red shades that read 7.8+ on the Taylor test. So I have my wife read the Taylor and I check with my meter. All readings so far are within .05 ph units calibrating only once per week. I also keep the probe in phosphate buffer storage solution as recommended by all the manufacturers of ph probes. You can find the unit I bought by searching Amazon or Google for "
Auto Calibration Mini Digital Pocket Pen Type PH Meter Multimeter Tester Hydro". There are also other brands at the bottom of the page. I have no idea which one is best.
Incidentally, if you are like me and need something other than the Taylor red shade color test for ph the auto calibrate meters are much easier to use... no more fiddling with the tiny adjustment screw. You just put the meter in the calibration fluid then press the calibrate button. The meter electronics do the rest. Just be sure you know what calibration fluids your meter uses. Some have an ability to calibrate with two different fluids like the one I have so you can calibrate above and below the typical reading you see. Hanna has a good selection of calibration fluids at a pretty good price and online gardening supply stores have more limited ph level calibration fluids at great prices.
I'll update later when I have more data and I hope these posts are helpful.
Chris
The pH meters incapable of a two point calibration are not worth having. Any that can, should be able to calibrate to a 4&7, or 7&10 two point Cal sequence. All of them should be stored wet, and frequently calibrated for optimum results.
I don't mean to hijack this thread, but I'm wondering if the cresol red scale is easier to read. Also, since many of us with new SW pools run high PH is a cresol red test kit better?
You shouldn't be running high enough pH to utilize one really. Your pool should be in the range you can use the phenol red pH test, even at the high end. If you can't, chances are you're running too high.
I have used this exact instrument for the previous 2 years. In my experience, the probe only lasts 1 season before it no longer holds calibration. I threw the first one away after year 1, and I threw the 2nd one away after year 2 (last year). I've already ordered another one for this year. The probe and a year's worth of standard calibration solution costs me about $25. I seem to recall spending about $25 per year in phenol red, so I guess it's break-even for me!
- Oct 25, 2015
- 5,213
- Pool Size
- 25000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-60 Plus
Jay,
I agree they're not necessarily more cost effective. But for me it's not all that much to pay for a test that works. I have color-blindness that make ph above 7.5 almost impossible to discern. Now that 2 point self calibrating systems are under $15 and even considering the $20 for a years worth of calibration it's just worth it for me. Also there's a big benefit that the meters measure accurately over 8.2 which the drop test can't do.
Thanks for your comment and I hope that helps clarify.
Chris
I wasn't making any disparaging remarks about the cost; in fact, I was doing just the opposite. The hidden thesis in my long-winded comment can be summarized as this: The probe is not very durable, but it's not very expensive...therefore, it's disposable. And even though it's disposable, it's cheap enough to not worry about getting a new one every year.
For my pool, pH is the only property that changes on a daily/weekly basis. Between the SWG and several water features, pH is always rising. This causes me to test pH quite frequently. The other properties are rock-solid, so I test for them infrequently.
I work to keep my alkalinity down, but pH is still constantly rising. I keep thinking about converting to the borate buffer, but I'm concerned about the effects on my dogs (who drink lots of pool water).
- Sep 23, 2015
- 1,598
- Pool Size
- 20000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Astral Viron V25
Two point for sure for me, its just a little more accurate as you get farther away from the calibration point. Having said that our pH range of 7.2 - 7.8 is fairly close to the 7.0 calibration point.
I'm sure this has been mentioned before but if you graph a series of points of known pH solutions against readouts from an uncalibrated pH meter you get a graph with a straight line. Calibrating to pH7 moves the line up or down where pH read equals pH actual only at pH7. As you get farther away from pH7 the difference between the read pH and actual pH increases. The second calibration point adjusts the slope making it a little more accurate farther away from the first set point. Please excuse my dodgy drawing.
Sammy2
0
Sammy2
0
I believe that after I get my pool stabilized on CyA and get the TA down, I'll be looking into one of these probes because I'll probably be out of phenol red by then!
Results from poollogger.com
FC: 13
CC: 0
PH: 7.2
TA: 110
CH: 500
CYA: 50
Temp: 71
Salt: 3300