What would you say this pH level is?

wireform

Silver Supporter
In The Industry
Aug 15, 2017
494
Spring Valley, NY
Just stare at it with a white background and the color falls in place either exactly or in between. It's not that complicated but definitely more reassuring then the electronic testers which when they're off you have no way of knowing untill recalibration
 

setsailsoon

LifeTime Supporter
TFP Guide
Oct 25, 2015
1,588
Stuart/FL
This is why I went to a Hanna pHep meter. There are several similar on the market and they're all very good. Just make sure it has auto calibration and temp compensation built in. The super cheap manual calibration meters I tried started to drift in months. I didn't try the one James suggested earlier. I did find manual adjustment screws to be difficult for me. Cheapest place I found was here but Google it yourself as there are a lot of sales at the stores that sell it. Yes, you do need to calibrate it (I did it each time at first) but calibration is simple. Now I calibrate approx weekly. It auto adjusts and compensates for temp. I keep a very small 1.75"X2" Nalgene screw-top container of calibration fluid, and change it out every 2 weeks or so. It's never off by more than .1 pH units. Way better than this red-purple challenged person can do with the phenol red test. Also, get some storage solution and put a few drops in the cap or at least some pool water if you're in a hurry. It's not good to let the electrode dry out after first use. My view is pH is one of the most important measurements for long term life of the plaster. It's worth the very small extra effort. And another plus is the result is not affected by FC level over 10.

I hope this helps.

Chris
 

SteelBlue

Well-known member
Jul 4, 2019
62
Scottsdale, AZ
So I bought the pH meter, just received it. It comes with a packet of powder that must be mixed with 250 cc deionized water (not included) in a glass container (not included) for calibration. So I have instead ordered a pre-mixed solution for calibration and some deionized water that is supposedly necessary for rinsing the sensor tip. A little more of a pain already. Hopefully it will eventually make life easier than struggling to match the color on the phenol red test.
 

SteelBlue

Well-known member
Jul 4, 2019
62
Scottsdale, AZ
I have the one linked in the above post, $15. It's not so good. Firstly, the instructions are horrible, they are a translation from a foreign country. Second, the calibration screw is deep-set below the plastic case and embedded in a circuit board. You have to fish the tiny screwdriver through the hole, hoping it lines up with the screw (and usually doesn't until the third or fourth try). Because the screw is on the back and precariously located deep in the case, you cannot adjust it while looking at the readout on the screen. You turn the driver a little, then turn the unit around to see what change has been made on the screen, lose the position of the screwdriver, and start all over again. Calibration of the unit is miserable. But it does seem to work and I'll keep it and use it. If I had it to do over again, I would go after the more expensive self calibrating device by Hanna.

I do prefer using this device to the phenol red color match. I know some folks say the color match is fine because you're just trying to keep the pH in an acceptable range. But a range does nothing to help you determine how much acid to add using the Pool Math calculator. If we are striving to do what TFP guidelines recommend, a range is not good enough...for me.
 

SteelBlue

Well-known member
Jul 4, 2019
62
Scottsdale, AZ
Oh I CAN get it now, but I just bought this one and will continue to use it for the time being.

But there is more bad news. I just calibrated the device again today to 7.0. Tested the pool water with it. The readout oscillated between 7.1 and 7.2. I compared this to the Taylor phenol red titration and got a match between 7.4 and 7.6. I repeated both tests and got the same values. Put the pH pen back in the calibrating solution and it was still 7.0. So the pen is definitely calibrated but is not even close to the phenol red test. BTW, I used both the 4 drop and the 5 drop method with phenol red. The 4 drop gave a better color match.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
Thousands, perhaps millions of users, use the phenol red test and it works just fine.

As far as not being able to calculate your dosage correctly using poolmath, you are overthinking that. The dosage has always been an approximation to get you safely close to the acceptable pH range TFP suggests. You should lose no sleep if your muriatic dosage results in a pH of 7.4 or 7.7 (or any other number in the 7's. Simply add a little more muriatic or aerate your pool if the results aren't quite where you want.

The tests found in the K-2006 and the TF-100 are not perfect but they are perfect"ly" adequate to maintain your pool in a crystal clear and sanitary condition
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,785
Northern NJ
But there is more bad news. I just calibrated the device again today to 7.0. Tested the pool water with it. The readout oscillated between 7.1 and 7.2. I compared this to the Taylor phenol red titration and got a match between 7.4 and 7.6. I repeated both tests and got the same values.
"A man with a watch knows what time it is. A man with two watches is never sure."

Now you need a tie breaker.
 

SteelBlue

Well-known member
Jul 4, 2019
62
Scottsdale, AZ
Sounds fine, and I have a lot of respect for your experience and opinions here. For what it's worth, I also used the Aquachek test strip and got a pH of 7.2, so if that is worth anything at all, it would seem the pH meter is more accurate.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,785
Northern NJ
Sounds fine, and I have a lot of respect for your experience and opinions here. For what it's worth, I also used the Aquachek test strip and got a pH of 7.2, so if that is worth anything at all, it would seem the pH meter is more accurate.
It doesn't matter. Any of those readings are within range and no acid is needed.

None of the tests are laboratory grade of accuracy. They are all inexpensive consumer products.