Ph Meter Question

DieselDuds · May 8, 2016

Let's start with this..

I have a bluelab ph pen and a Oakton eco ph pen I was gifted from a buddy. I calibrate my blue with the 7.01 fluid and it calibrates. I also turned the pH pen (upside down ) to see if the probe was dirty which it wasn't . Buy there was an air bubble within the probe and it arose to the tip of the probe. Could this cause a problem. The reason I say this is. I calibrated the Oakton with the 7.01 and I'm getting a .03 difference on the ph when testing the resivor water.

Is my blue right. Is the Oakton right?

Og Gong · May 8, 2016

DieselDuds said:
Let's start with this..

I have a bluelab ph pen and a Oakton eco ph pen I was gifted from a buddy. I calibrate my blue with the 7.01 fluid and it calibrates. I also turned the pH pen (upside down ) to see if the probe was dirty which it wasn't . Buy there was an air bubble within the probe and it arose to the tip of the probe. Could this cause a problem. The reason I say this is. I calibrated the Oakton with the 7.01 and I'm getting a .03 difference on the ph when testing the resivor water.

Is my blue right. Is the Oakton right?

Lol my hydro store guy took 6 top ph pens to test accuracy and all of them were off even after calibrating. I went back to the cheap liquid ph tester after that.

Growin Grass · May 8, 2016

.03 or .3
.03 wouldn't be anything to sneeze at .3 on the other hand could be a significant difference. I ask because my oakton doesn't read to the hundredth. Like gong said though, they will all read a little different. I personally don't trust myself with the color drops

hermit186 · May 8, 2016

Think I have 100 marbles of those you lost 2 is not that big of a difference but you need to keep both standing in water when not in use if the probe dries clear dry will respond strange for a coupla hours (some of the companys reccomand 24 hrs before you use it), also get some drops and learn with your meter how to read the colors. Someone here recommended me that here and then one day mine quit was glad I did. Also Calibrate often till your get used to it. Only now and then do I use it the drops are better.

Ph/ppm/EC is very important how ever all changes in a plant happen over time for a while till your used to the electronic way
test everything you can in and out water before nutrients and after get the feel of it. Hell take a leek and test it.
Read some here about it. Rapid changes in ph will doom your grows. Remember to wait after adjustments before rechecking and shaking is not enough let it stand a bit.
If you like chemistry then you using both up and down at the same time is NOT A REAL GOOD IDEA.
Went the water goes in and comes out with a higher PH/ppm/EC your started down a slope that leads to root problems.
It means there are nutrients building up and not being use.
In time you will flush and if you do you free up all those locked nutrients.

Oh and last thing if is not one of the best PH meters it will be from china.
I have had 3 none lasted and were for a quick check but I mix with drops

ShroomKing · May 8, 2016

Og Gong said:
Lol my hydro store guy took 6 top ph pens to test accuracy and all of them were off even after calibrating. I went back to the cheap liquid ph tester after that.

^^^^ True wisdom

I'm of the opinion that no pH pen has the accuracy you need.

My opinion based on nothing more than the old proverb "you get what you pay for".
Lol

MrBlah · May 8, 2016

If you only used a single solution at 7.01 pH to do the calibration, then you will not have accurate results. You need to calibrate with two different stock solutions. Typically, a 7.0 and 10.0 pH.

ken dog · May 8, 2016

Or a 7&4...and the way pH is measured, that's about as accurate as you're going to get.
It is measuring the potential hydrogen in a solution... Not accurate at all, yet as accurate as it gets.

DieselDuds · May 8, 2016

Correction!!!!! Not .03, I meant .3

DieselDuds · May 8, 2016

ken dog said:
Or a 7&4...and the way pH is measured, that's about as accurate as you're going to get.
It is measuring the potential hydrogen in a solution... Not accurate at all, yet as accurate as it gets.

I have the 7.01 and 4.0 solution. My old bluelab pend used both calibration solutions to calibrate. This new bluelab pen only asks for the 7.01 even in the instructions. Weird. Did they upgrade the programming?

MrBlah · May 8, 2016

ken dog said:
It is measuring the potential hydrogen in a solution... Not accurate at all, yet as accurate as it gets.

This is incorrect. Precise measurement of pH is part of International Standard ISO 31-8: https://en.wikipedia.org/wiki/ISO_31-8 and it is very accurate.

There are many pH meters that have an accuracy of +/- 0.01 pH or around there. The thing is, they are laboratory grade instead of consumer grade. So, paying $40 for a pH meter won't be that accurate. Paying $200-700 will.

Companies like Cole Palmer, Edmund Scientific, Oakton, Hach, YSI, for example, each produce portable or benchtop pH meters with an accuracy of +/- 0.01 of the real pH of the solution. They also include automatic temperature compensation, something cheap meters, usually <$100, do not include.

MrBlah · May 8, 2016

DieselDuds said:
I have the 7.01 and 4.0 solution. My old bluelab pend used both calibration solutions to calibrate. This new bluelab pen only asks for the 7.01 even in the instructions. Weird. Did they upgrade the programming?

They just made it cheaper. No change in programming will allow you to accurately calibrate a pH meter with only 1 stock solution.

ken dog · May 8, 2016

MrBlah said:
This is incorrect. Precise measurement of pH is part of International Standard ISO 31-8: https://en.wikipedia.org/wiki/ISO_31-8 and it is very accurate.

There are many pH meters that have an accuracy of +/- 0.01 pH or around there. The thing is, they are laboratory grade instead of consumer grade. So, paying $40 for a pH meter won't be that accurate. Paying $200-700 will.

Companies like Cole Palmer, Edmund Scientific, Oakton, Hach, YSI, for example, each produce portable or benchtop pH meters with an accuracy of +/- 0.01 of the real pH of the solution. They also include automatic temperature compensation, something cheap meters, usually <$100, do not include.

Nope... and you have Illustrated one reason why with regards to temperature affecting measurements.

The other thing, is that pH is always in flux, and the meter only measures the potential of the solution.

It's not the instrument that is doing the measuring, it is the measurement itself.

MrBlah · May 8, 2016

ken dog said:
Nope... and you have Illustrated one reason why with regards to temperature affecting measurements.

The other thing, is that pH is always in flux, and the meter only measures the potential of the solution.

Yes, a feed solution for plants is going to be in a state of change while it is being used. But, before that point, during the preparation of the solution, chemical equilibrium is reached. And that is the only reference point we have unless we are using a recirculating hydroponics system.

ken dog said:
It's not the instrument that is doing the measuring, it is the measurement itself.

So, you think that ISO 31-8 is incorrect? And that it should be changed because it's not accurate at all? On what basis do you make these claims that an international standard is wrong? Do you even understand the standard? Feel free to share because you've chosen just about the best forum to argue about that.

ken dog · May 8, 2016

The iso standard is a red herring... Has nothing to do with the point.
I'm glad you agree that pH is always in a state of flux.

MrBlah · May 8, 2016

ken dog said:
The iso standard is a red herring... Has nothing to do with the point.

Then what point are you making? Because you have not been clear at all.

DieselDuds · May 8, 2016

Ok ok ok. So what I have gathered from this is ph is always in a state of Flux, agreed on that. I always let my solutions mix well before I give it an ok and try to get the best reading possible. But I guess I'll just stay with my bluelab pen and calibrate it often and just hope for the best.

ken dog · May 8, 2016

MrBlah said:
Then what point are you making? Because you have not been clear at all.

The point I am trying to make is that small differences in pH readings between the same brand of pens, are insignificant.

MrBlah · May 8, 2016

DieselDuds said:
Ok ok ok. So what I have gathered from this is ph is always in a state of Flux, agreed on that. I always let my solutions mix well before I give it an ok and try to get the best reading possible.

Waiting for chemical equilibrium to occur is always a good practice. So, you're definitely doing it right.

ken dog said:
The point I am trying to make is that small differences in pH readings between the same brand of pens, are insignificant.

I think for our application, this is a good outlook to have.

We are agreed!

PhatNuggz · May 9, 2016

hermit186 said:
Think I have 100 marbles of those you lost 2 is not that big of a difference but you need to keep both standing in water when not in use if the probe dries clear dry will respond strange for a coupla hours (some of the companys reccomand 24 hrs before you use it), also get some drops and learn with your meter how to read the colors. Someone here recommended me that here and then one day mine quit was glad I did. Also Calibrate often till your get used to it. Only now and then do I use it the drops are better.

Ph/ppm/EC is very important how ever all changes in a plant happen over time for a while till your used to the electronic way
test everything you can in and out water before nutrients and after get the feel of it. Hell take a leek and test it.
Read some here about it. Rapid changes in ph will doom your grows. Remember to wait after adjustments before rechecking and shaking is not enough let it stand a bit.
If you like chemistry then you using both up and down at the same time is NOT A REAL GOOD IDEA.
Went the water goes in and comes out with a higher PH/ppm/EC your started down a slope that leads to root problems.
It means there are nutrients building up and not being use.
In time you will flush and if you do you free up all those locked nutrients.

Oh and last thing if is not one of the best PH meters it will be from china.
I have had 3 none lasted and were for a quick check but I mix with drops

Good input, especially when over adjusting with acid, then correcting with base.

Do you have any experience with pH and temps? I'm thinking higher temps will mean higher pH, but I haven't tested it. This grow I am doing a much better job of maintaining cool rez temps and the plants look great

MrBlah · May 9, 2016

PhatNuggz said:
Good input, especially when over adjusting with acid, then correcting with base.

Do you have any experience with pH and temps? I'm thinking higher temps will mean higher pH, but I haven't tested it. This grow I am doing a much better job of maintaining cool rez temps and the plants look great

With a 10°C temperature change, you may see up to a 0.2 shift in pH.

Ph Meter Question

Ph Meter Question

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Og Gong

Rip Geologic

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ShroomKing

Best of luck. Peace

MrBlah

ken dog

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MrBlah

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ken dog

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Ph Meter Question

Ph Meter Question

DieselDuds

Og Gong

Rip Geologic

Growin Grass

hermit186

ShroomKing

Best of luck. Peace

MrBlah

ken dog

DieselDuds

DieselDuds

MrBlah

MrBlah

ken dog

MrBlah

ken dog

MrBlah

DieselDuds

ken dog

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