Measuring PH accurately

mitch08

Well-known member
Jun 30, 2008
391
Suffolk County, NY
I'm having a difficult time getting an accurate reading of my PH.
I mean, I never thought I was color blind until I try telling the difference between 7.4, 7.6, and 7.8. They are soooo close.

I feel like there is a big difference and Im thinking that mine might be dark enough to be 7.8. But Im not sure. Is there a trick or different test to find out exactly what it is?

The chlorine test is the same to me. All those yellows look identical to me :hammer:
The difference with the chlorine is that I have the 100 test kit which is amazing and I just do the chlorine drop test and find out exactly what is going on. For instance, the other day I thought my FC was over 5 from the yellow test. It seemed dark. But that didnt make sense so I grabbed the chlorine drop test and it was 3.5 which was perfect.

But I cant do that with PH.......

Any advise on this?

Thanks guys!!!
 

duraleigh

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Hey,

Short of a VERY expensive digital meter, you just have to "wing it".

Getting someone else's opinion or practicing several times is always a good idea.

Fortunately, the difference between 7.3 and 7.6 is of virtually no consequence for our purposes with pools so if you get close, you're fine.
 

4JawChuck

Well-known member
Jun 13, 2010
223
Winnipeg, Manitoba, Canada
A little trick I learned a long time ago from an old timer whose eyes were about the same as mine now was to read the color scale in front of a grey scale panel, he actually used a newspaper which had a large section of grey area on it. Today I use a photo grey panel that I use for photography behind the scale since I have a few of them and use them for the photo hobby but really anything that adds a grey tint works well for distinguishing color levels. It doesn't help with color distinction as much as it helps with darkness levels which is what is the hardest to see for tired/older eyes.

Give it a try and make sure to use sunlight instead of incandescent or fluorescent light, see if it helps.
 

PaulR

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Jan 11, 2009
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Cupertino, CA
If you are using the OTO (yellow drop) chlorine test at the same time as the pH test, read pH first. Staring at the yellow before looking at the red/orange can change your perception due to color fatigue. (I had the same pH test go from 7.5 to about 7.9 after looking at the OTO.)
--paulr
 

mitch08

Well-known member
Jun 30, 2008
391
Suffolk County, NY
4JawChuck said:
A little trick I learned a long time ago from an old timer whose eyes were about the same as mine now was to read the color scale in front of a grey scale panel, he actually used a newspaper which had a large section of grey area on it. Today I use a photo grey panel that I use for photography behind the scale since I have a few of them and use them for the photo hobby but really anything that adds a grey tint works well for distinguishing color levels. It doesn't help with color distinction as much as it helps with darkness levels which is what is the hardest to see for tired/older eyes.

Give it a try and make sure to use sunlight instead of incandescent or fluorescent light, see if it helps.
I will definitely try that. It makes perfect sense actually. I have a home theater that I use a grey scale screen on because it helps with the darkness levels and color distinction :)

Thanks for your help!!!!
 

mitch08

Well-known member
Jun 30, 2008
391
Suffolk County, NY
PaulR said:
If you are using the OTO (yellow drop) chlorine test at the same time as the pH test, read pH first. Staring at the yellow before looking at the red/orange can change your perception due to color fatigue. (I had the same pH test go from 7.5 to about 7.9 after looking at the OTO.)
--paulr
That's interesting. I always do both tests at the same time and Im pretty sure I look at the Chlorine first just by habit. Ill try it that way and see if it makes a difference.

Love the gray scale idea though.
 

Barbara C

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Jun 2, 2010
124
Southern Indiana
I have a grow light for starting plants indoors that helps me. I put the block under it with white background and the colors pop. I was suspicious at first so I would test the chlorine with the drop test and was dead on every time. They're cheap to boot at walmart.
 

Richard320

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Jan 6, 2010
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I get my best results holding the block at arm's length with a white resin patio chair as the background and squinting until the numbers are unreadable. I can tell if I'm closer to 7.5 or 7.8 no problem.
 

duraleigh

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Blue sky works best for me, but I think it is a matter of finding a technique and then sticking with it over and over and you will get proficient.
 

VinceL

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Apr 28, 2012
207
Newton, NC
The FC/pH test kits include a white blotting cloth. I never use it and just save it to hold behind the tubes so I have a nice white background. And, as others have said I read it in natural light. It is amazing how much different the colors look under natural, incandescent or fluorescent lighting.
 

duraleigh

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the colors going from low pH to high pH are....

yellow 6.8 and lower
yellow orange 7.0
orange 7.2
orange red 7.4-7.5
red 7.6-7.8
red violet 8.0
violet 8.2 and higher

These threads come up often.....naming the colors seems to help some folks.
 

mrcarcrazy

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Jan 21, 2014
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Odessa, TX
I use the white brick of my house. I have considered buying an electronic meter...but that will take significant research before I jump.
 

dschlic1

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Oct 5, 2007
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Valrico, FL
An electronic pH meter is not all that expensive. A low end model can be had for under $20. You will of course have to calibrate it on a regular basis.
 

marty

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Jul 10, 2012
240
CA
An electronic pH meter is not all that expensive. A low end model can be had for under $20. You will of course have to calibrate it on a regular basis.
How do you calibrate it? I was given one without operating manual.
 

JasonLion

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May 7, 2007
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Silver Spring, MD
The least expensive electronic meters can't be calibrated, and so are useless. The mid-rage ones all use different sequences to calibrate, so you need to find a copy of the manual (often available online).

I would not trust a PH meter that costs less than $100. It might work for a while, but the less expensive ones are amazingly unreliable. They provide the illusion of precision, while lacking any true dependability.

Unless you have significant color blindness, or need to measure PH several times a day every day, the color matching PH test really is your best choice. The extra effort required to keep the electronic meters in calibration is more trouble than it is worth otherwise.
 

ps0303

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In The Industry
Jul 6, 2011
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FL
For years now I have used the Lamotte ColorQ. It is very good and I do check from time to time with a regular test kit and I have to say, it's always close if not almost right on the money.
 

marty

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Jul 10, 2012
240
CA
There needs to be a TFP youtube vid on how to post youtube vids, lol.
Is this a decent brand? are those pills still good?
Heres the link http://youtu.be/vvNIGh-qZek

- - - Updated - - -

For years now I have used the Lamotte ColorQ. It is very good and I do check from time to time with a regular test kit and I have to say, it's always close if not almost right on the money.
So out of the two what one would be the definite reading?
 

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