Make your own pH standard solution

[lightmaster]

Would it be possible to make your own pH standard solution? Say by taking X amount of distilled water and adding Y amount of muriatic acid to get it a specific pH.

 

[kimkats]

I can do one better for you! Look here: R-7062 pH Standard 7.2 (2 ounces) They also offer the other tests!

I am sure you could make some but have no idea how so this was the closest I could come.

Kim

 

[Leebo]

While in theory you could it’s alot more effort than it’s worth. Your measurements would need to be amazingly accurate and the equipment needed to measure would likely out-cost just buying the standard.

 

[Donldson]

Distilled water absorbs CO2 from the atmosphere forming carbonic acid, so the pH will be lower than 7 right off the bat. So adding MA to that would create a pretty low pH sample for pool use. You would actually be looking to raise the pH.

Aside of that, MA loses strength as it sits. So what you are buying is almost certainly not exactly 31.5% HCl. When you are dealing with something as large as a pool with the various pH buffers that are dissolved in it (TA, borates, etc) slight variations in acid strength will have fairly minor effects. But if you are trying to change the pH of a gallon of water you are going to be measuring your MA by the micro-liter. So I hope you have some well calibrated equipment and perfectly measured MA strength.

But even if you were to have all of that, there is one final question: how would you test the solution to make sure it is accurate?

 

[JoyfulNoise]

pH standards are created via buffer chemistry by using an acids and its conjugate base. For example, the acetic acid/sodium acetate system or dihydrogen phosphate / hydrogen phosphate system. The point in using a mixed chemistry is so that the buffering present resists changes to pH when other chemicals are added. There are buffer systems for almost any pH value and specific procedures for setting an exact pH value.

As others have said, the cost of the chemicals and equipment to make a pH standard would far outweigh its usefulness.

Why do you need a standard anyway? The pH reagent is incredibly stable and not prone to errors.

 

[lightmaster]

Perfect math would make it exactly the right pH.... ignoring the many variables, lol. Just did some rough calculations and it would be something like 5 microliters to drop 1 liter of pure distilled water to 6.2 pH. So short of running back to my college chem lab, not gonna be making it myself, lol.

On another note, what is the shelf life of the pH standard solution on tftestkit's site? Gonna use it to periodically calibrate my pH meter.

 

[JoyfulNoise]

You can also by packets of powdered pH calibrating standards that you mix with water (4.1, 7 and 10) to calibrate any probe with ... assuming your probe can do a 2-point calibration.

 

[Dirk]

I expressed this thought elsewhere here, regarding a salt meter. I'm missing something about these gizmos... Why the appeal? Batteries... calibration... reliability... storage... an additional procedure to deal with... initial cost...

The pH drop test is the only one I actually like doing. It's so easy, so fast, and plenty accurate for a pool. And I've already taken the sample, I've got the kit out to do the FC test anyway. What is the advantage of a pH meter that I'm not seeing?

 

[lightmaster]

Just found the powders which would be exactly what I need.

Dirk, I'm terrible at determining the difference between the shades of red/pink on the pH test. Can't ever tell if it's halfway above or halfway below the closest color match. I can tell the difference between other colors, just shades of red are difficult for me

 

[Dirk]

Of course, I didn't consider those with color-seeing challenges. I don't know if this would help in your case. I was struggling with the pH color comparison, too, at first. Marty (my TFP mentor) suggested I use four drops instead of five. That helped a lot. I also test inside, under LED light. I hold a white card behind the test vial and move it around a bit until I get the best angle of light shining through the water and the swatches. And then as I'm looking at the colors, I'm thinking "Is that more yellow or more purple than the closest color swatch? I can now see a ±0.1 reading that way, where before I couldn't even tell where I was on the scale at all!

 

[woodyp]

Reagents are guaranteed for a year.

 

[mdogan]

4 drops should be good for Taylor kit i believe, thanks for heads up.
for white background I'm using laptop screen. it is really helpful

 

[Dirk]

4 drops should be good for Taylor kit i believe, thanks for heads up.
for white background I'm using laptop screen. it is really helpful

Ooh, laptop screen. Good one.

 

[lightmaster]

4 drops should be good for Taylor kit i believe, thanks for heads up.
for white background I'm using laptop screen. it is really helpful

That's a good idea, I've been trying with a piece of paper taped to the wall, but my off-white led lights mess with the colors a bit. Gonna try opening a new document in notepad on my laptop and try with that as the background next time.

 

[kimkats]

Danger Will Robinson, Danger! Make sure you put something OVER the keyboard for WHEN you spill or slosh or ?? water. That is your PSA for the day! LOL

 

[lightmaster]

Danger Will Robinson, Danger! Make sure you put something OVER the keyboard for WHEN you spill or slosh or ?? water. That is your PSA for the day! LOL

Nah, I figured the sparks would help with backlighting the sample and making it easier to read, lol.

 

[Dirk]

Danger Will Robinson, Danger! Make sure you put something OVER the keyboard for WHEN you spill or slosh or ?? water. That is your PSA for the day! LOL

Right? It's gotta happen! I was also going to point out, based on how I use my laptop (changing the brightness all the time), and the way my computer screen's backlight degrades over time, or the fact that I buy a new one once in a while... that challenges my repeatability and consistency goals. I think I'll stick with my LED light strip: bright, color-neutral, repeatable, consistent light source good for 50,000 hours. It'll be shinin' longer than I will be! And it's over my drippy mess, not under it.

I do like the idea of comparing in front of a light source, though. I have to use a white card to reflect the light source though the vials, which is not as good, for sure...

 

[bizzle]

A laptop screen (and the LED) is going to be on the cool side (tending towards blue) whereas sunlight is warm (tending towards green). The LED can achieve better approximation of colors depending on it's CRI rating.

One way to calibrate your meter when you don't have access to a standard would be to compare it to the drop test results. I don't know how frequently we should be calibrating our probes but I don't think it's a huge concern. I don't remember calibrating my TDS probe ever and my corals survived and some even thrived

The instructions crack me up, though. The section discussion the calibration has a typo where the period should be a colon ("You should calibrate whenever." s/b "You should calibrate whenever:") and one of the criteria is "accuracy matters" or something along those lines.

 

[peirek]

I too have a devil of a time distinguishing the reds on the upper end of pH scale (7.8+). I have been experimenting with how many drops of base demand it takes to drop into 7.6/7.4 area (which I can distinguish quite well) in an attempt to help better read the reds. I am not sure I have seen great success doing this however. Still working on getting more data.

Does the TF-100 kit have a different pH testing scale than the K-2006C? The K-2006 goes to 8.0 only and the delta in reds between 7.8 & 8.0 is next to impossible for me to distinguish.

 

[lightmaster]

I too have a devil of a time distinguishing the reds on the upper end of pH scale (7.8+). I have been experimenting with how many drops of base demand it takes to drop into 7.6/7.4 area (which I can distinguish quite well) in an attempt to help better read the reds. I am not sure I have seen great success doing this however. Still working on getting more data.

Does the TF-100 kit have a different pH testing scale than the K-2006C? The K-2006 goes to 8.0 only and the delta in reds between 7.8 & 8.0 is next to impossible for me to distinguish.

TF100's pH test is a bit easier as far as the procedure. Fill the vial and add 4-5 drops of Phenol Red. No adding base demand drops or anything else.



I ended up buying a pack of 5 sets of pH buffer powders on Amazon and calibrated my pH meter. Figure I'll calibrate it once a month. After calibrating it again, it reads the same as TF100 pH test (or so my wife says, lol).