Can’t get accurate results on K-1776 salt test

[Rockstead]

So based on pool store test I should be around 1200PPM, which is typical after I open my pool after the winter.

I’m struggling to use the K-1766, in following the directions of the kit and I fill to the 10nl mark, I add my one drop of R-0630 to turn the sample yellow and I’m adding the R-0718 until it is supposed to turn to a milky salmon brick red according to the instructions, when I use the speed stir I end up having a reading of 2000PPM before it turns to the color in the attached, and when I swirl by hand I sometimes achieve the same thing with only 8 drops, and sometimes even more.

I can’t figure out what I’m doing wrong to make this so inaccurate.

 

[ajw22]

Hand swirling is much more inaccurate then using the Speed Stir.

Trust the Speed Stir result. Your salt is 2,000 ppm.

 

[sacredcow]

This method is based on Standard Methods 4500-Cl B- Argentometric Method. Silver chloride is precipitated until the chlorides are consumed, at which point red silver chromate begins to form. Per Standard Methods, "pinkish yellow" is technically the endpoint you're looking for, but "brick red" is very commonly thrown out there as a descriptor and often causes people to over-titrate a bit.

You're forming precipitates that are causing the resulting color, so the speed stir is preferable here. Harder to keep solids in suspension via swirling.

Analyzing a known standard so you have a mental picture of the true endpoint helps.

 

[Jimrahbe]

Rock,

Unlike other tests, you are not supposed to keep adding drops until the color no longer changes. You should stop, when the drop causes the color to change from yellow to pinkish.

When using the speed-stir, I find that as you get close to the salt level, the color will "flash" from yellow to pinkish and then almost instantly change back to yellow. The first time it changes to pinkish and stays that way, you are done.

I find the salt test to be the most accurate and repeatable test there is...

Thanks,

Jim R.

 

[Rockstead]

Rock,

Unlike other tests, you are not supposed to keep adding drops until the color no longer changes. You should stop, when the drop causes the color to change from yellow to pinkish.

When using the speed-stir, I find that as you get close to the salt level, the color will "flash" from yellow to pinkish and then almost instantly change back to yellow. The first time it changes to pinkish and stays that way, you are done.

I find the salt test to be the most accurate and repeatable test there is...

Thanks,

Jim R.

Hey Jim,

That’s my issue, I keep adding drops until it gets to be milky and yes it flashes that pinkish salmon for a second but then it all goes back to being that milkish color and then it ends up going that dark red like the picture I attached which I understand means I’ve put too much.

Yet in the YouTube videos I found the person doing the demonstration can get it to remain in a solid pinkish salmon color without it going back to milkish.

 

[Saturn94]

Hey Jim,

That’s my issue, I keep adding drops until it gets to be milky and yes it flashes that pinkish salmon for a second but then it all goes back to being that milkish color and then it ends up going that dark red like the picture I attached which I understand means I’ve put too much.

Yet in the YouTube videos I found the person doing the demonstration can get it to remain in a solid pinkish salmon color without it going back to milkish.

You might be interested in this thread (start on page 5, post 100) where I was having issues using the K1766 test.

Squeeze last bit of life out of cell?

Update: Today the new T15 cell seems to be working fine on the T15 setting. Out of curiosity, I tried another test using the K1766 Taylor kit, being very careful, making sure to mix very well between drops, and dispensing drops slowly to ensure proper drop size. It’s still reading 1000ppm...

www.troublefreepool.com

 

[mgtfp]

You might be interested in this thread (start on page 5, post 100) where I was having issues using the K1766 test

You mention in the post you are quoting, that you didn't trust the K1766 test based on your experience with salt taste. I think you need to be a bit careful there. The K1766 only tests for Cl^-, but as far as I know, the taste of salt also depends on the Na⁺ that comes from dissolved table salt. Other salts also provide a sense of saltines, but only NaCl gives you the real deal.

There are other sources of Cl^- in a pool by adding liquid or granular chlorine or muriatic acid, the concentration of Cl^- and the salt taste don't necessarily have to match.

I would trust the K1766 test.

 

[Saturn94]

You mention in the post you are quoting, that you didn't trust the K1766 test based on your experience with salt taste. I think you need to be a bit careful there. The K1766 only tests for Cl^-, but as far as I know, the taste of salt also depends on the Na⁺ that comes from dissolved table salt. Other salts also provide a sense of saltines, but only NaCl gives you the real deal.

There are other sources of Cl^- in a pool by adding liquid or granular chlorine or muriatic acid, the concentration of Cl^- and the salt taste don't necessarily have to match.

I would trust the K1766 test.

While I did mention I thought salt taste would be more noticeable based on the K1766 result, I didn’t mean that taste was an accurate way to determine salt level. If you read the rest of the thread you will see how it evolved. There were multiple other more important factors that led to my suspicion that something was going on with the K1766 test (ie, it was out of line with other test methods, as well as reading high when testing a standard solution).

Joyful indicated that my use of a metal sequestrant (Jack’s Magic Purple Stuff), and perhaps combined with not using a SpeedStir, were likely why the K1766 was reading quite a bit higher than other test methods.

Personally, I’ve concluded JamesW’s advice will serve me best going forward.

I never trust any single test.

I always want to see several tests that are in close agreement before I will trust a reading.

I will usually use the SWG, a meter and a K-1766 to test to make sure that they are all in agreement.

 

[mgtfp]

Yes, @Saturn94 , I didn't read the whole thread. Thanks for the summary, glad it got resolved.

 

[Saturn94]

Yes, @Saturn94 , I didn't read the whole thread. Thanks for the summary, glad it got resolved.

The experience was certainly educational. I hope the OP gets something useful out of it.

Btw, I found your information about what affects our taste of salt interesting.

 

[Rockstead]

Rock,

Unlike other tests, you are not supposed to keep adding drops until the color no longer changes. You should stop, when the drop causes the color to change from yellow to pinkish.

When using the speed-stir, I find that as you get close to the salt level, the color will "flash" from yellow to pinkish and then almost instantly change back to yellow. The first time it changes to pinkish and stays that way, you are done.

I find the salt test to be the most accurate and repeatable test there is...

Thanks,

Jim R.

Jim,

Based on this photo, is this the pink colour I should be looking for?

 

[Rockstead]

Jim,

Based on this photo, is this the pink colour I should be looking for?

Still hoping someone can answer me on the color

I should also mention my water is freezing in case temp plays a part in inaccurate testing.

 

[Jimrahbe]

Rock,

I can't answer your question, as I can't remember the exact color.. I am not really looking for a specific color, but rather the point were it first changes and does not change back.

I'd take a double sample and run a test when cold, and then run test at room temp, and see if you get the same results. My "guess" it that the test will be sluggish when cold. Just a guess, as I have never run the test with cold water. I don't care what the salt level is when the water is cold. I only worry about it just before I turn my SWCG back on in the Spring.

Thanks,

Jim R.

 

[Bperry]

Jim,

Based on this photo, is this the pink colour I should be looking for?

It looks close but like Jim said the color doesn’t matter. You only add drops until the color changes and it changes like a light switch. Don’t add any more after it changes. Imagine a seagull flying overhead and it drops…one in your drink and ruins it…you don’t want to touch it after that. It’ll look just like that.

 

[sacredcow]

Still hoping someone can answer me on the color

I should also mention my water is freezing in case temp plays a part in inaccurate testing.

With a test that counts drops, you're not getting plus or minus 1 ppm accuracy, so don't over-think it. As you begin to add drops, the solution will go cloudy but will still be yellow. As you near the endpoint, you will see flashes of pink/red with each drop that disappear. Still nearer, the flashes of pink/red will linger longer before reverting back to yellow. When there is a discernable pink/red that does not go away, you are finished. This final color may not be exactly the same every time with a drop test.

As for temperature, I don't think it matters enough to worry about. Temperature is not listed as a consideration in Standard Methods for this technique.

 

[fishbait]

Jim,

Based on this photo, is this the pink colour I should be looking for?

I did my fisrt salt test last night. I went from yellow, to a salmon, and then to a brick red like shown in your picture. To me the instructions are confusing. Salmon and brick red are two very different colors in my mind. So which is it? I've read that the first change should be the one, not the next change to brick red. Confused.

 

[Bperry]

I did my fisrt salt test last night. I went from yellow, to a salmon, and then to a brick red like shown in your picture. To me the instructions are confusing. Salmon and brick red are two very different colors in my mind. So which is it? I've read that the first change should be the one, not the next change to brick red. Confused.

It’s the first change to a different color. The exact color doesn’t matter.

 

[Rockstead]

I did my fisrt salt test last night. I went from yellow, to a salmon, and then to a brick red like shown in your picture. To me the instructions are confusing. Salmon and brick red are two very different colors in my mind. So which is it? I've read that the first change should be the one, not the next change to brick red. Confused.

I agree completely! and then it says if you went too far, the color will be brown and that’s what I feel my color changed resembled more compared to salmon.

In your case you say it actually changed to Salmon, so at least you know that is what you are looking for, in my case it will go from the milky color to the brick red from my picture, when I add the drops and using my speedstir, it flashes the salmon color but reverts to the milky and finally the brick red.

Worse is that there are almost no examples of these colors when you search YouTube or elsewhere, and the one example on YouTube and the person actually achieved what I would perceive as an actual salmon color and that’s what really makes me feel mine is brown and brown means too far according to the instructions.

 

[Bperry]

I agree completely! and then it says if you went too far, the color will be brown and that’s what I feel my color changed resembled more compared to salmon.

Worse is that there are almost no examples of these colors when you search YouTube or elsewhere, and the one example on YouTube and the person actually achieved what I would perceive as an actual salmon color and that’s what really makes me feel mine is brown and brown means too far according to the instructions.

The whole point of the test is to avoid trying to match exact colors. That’s why the OTO chlorine test is so hard and not very accurate. The goal is a color “change”. People perceive brick, red, brown in different ways and so they’ve set up the change to be milk —> “red-ish, salmon-ish,brown-ish” color. Don’t over think it.

 

[fishbait]

The whole point of the test is to avoid trying to match exact colors. That’s why the OTO chlorine test is so hard and not very accurate. The goal is a color “change”. People perceive brick, red, brown in different ways and so they’ve set up the change to be milk —> “red-ish, salmon-ish,brown-ish” color. Don’t over think it.

Agree, that's what makes this forum great, clearing up the confusion! I'll stop at the first color change now and not strive for brick red. Brick red and salmon are different colors, and both can happen in the test. That is the cause for my confusion. I'll run the test again tonight and if I get both colors again ill take a pic of each and post for reference of all who read the thread.