Taylor K-1766 Sodium Chloride test kit accuracy

[dooger54]

Just received this test kit and am now testing my salt water pool for the first time. I have always relied on my local pool store to test the salt level before. I have run two tests, about one week apart, and they both have come back with a salt level of right at 5200. High obviously. My SWG recommends around 3500-4000.

The SWG also measures the salinity and it reports 3600. My last test by the local pool store was around 3500. Am I doing something wrong? Concerned why the Taylor kit is showing so much higher.

 

[Jimrahbe]

d,

Are you hand swirling or do you have the speed-stir? I use the speed-stir and find that the Taylor K-1766 is accurate and repeatable. I find it one of the easier tests, as the change happens almost instantly.

Thanks,

Jim R.

 

[dooger54]

d,

Are you hand swirling or do you have the speed-stir? I use the speed-stir and find that the Taylor K-1766 is accurate and repeatable. I find it one of the easier tests, as the change happens almost instantly.

Thanks,

Jim R.

I use a speed stir. I agree, the test should be easy.

I have noticed that when the color finally turns to salmon the liquid is “curdled”. Not smooth. Bad chemicals?

 

[JoyfulNoise]

Are you using a 10mL water sample? The test uses 10mL as the standard volume, not 25mL like the other Taylor tests. The milky curdled solution is normal, that’s the silver chloride precipitate that forms when you add the silver nitrate drops.

Are you recording the number of drops as soon as it goes from yellow to reddish? You’re not waiting for a specific color, the test ends as soon as you get the first stable reddish color. It can look brick red or salmon red, but it’s just when it transitions from yellow to red.

 

[dooger54]

Are you using a 10mL water sample? The test uses 10mL as the standard volume, not 25mL like the other Taylor tests. The milky curdled solution is normal, that’s the silver chloride precipitate that forms when you add the silver nitrate drops.

Are you recording the number of drops as soon as it goes from yellow to reddish? You’re not waiting for a specific color, the test ends as soon as you get the first stable reddish color. It can look brick red or salmon red, but it’s just when it transitions from yellow to red.

Yes I am using the 10ml sample size. Good to know the curdled solution is normal. I am counting the drops and stopping as soon as the sample turns a reddish color. 26 drops.

I guess maybe my salinity level is just high. Wish there was some other way to verify but I think I am doing everything right.

 

[JoyfulNoise]

I would agree then that your salinity is 5200ppm. Pool store tests are almost always wrong as they typically use strips which are much less accurate.

I would verify with one more test and here’s how I would do it - as accurately as you can possibly measure I would dilute a pool water sample 1:1 with distilled water. That will cut the salinity in half. Then I would redo the test. You should get 12-13 drops. If so, then your pool water definitely has high salinity.

The next question is this - how old is your cell? Have you pulled it out recentky to check the plates for scaling? Do these CircuPool SWGs use a separate conductivity probe for salinity? If so, is it in good shape or corroded?

 

[Jimrahbe]

d,

You could add 1.6 oz of salt to 5 gallons of water and mix real well... Should be about 2400 ppm...

Thanks,

Jim R.

 

[dooger54]

d,

You could add 1.6 oz of salt to 5 gallons of water and mix real well... Should be about 2400 ppm...

Thanks,

Jim R.

I was thinking about that, making my own calibration solution. Just standard table salt would work?

 

[dooger54]

I would agree then that your salinity is 5200ppm. Pool store tests are almost always wrong as they typically use strips which are much less accurate.

I would verify with one more test and here’s how I would do it - as accurately as you can possibly measure I would dilute a pool water sample 1:1 with distilled water. That will cut the salinity in half. Then I would redo the test. You should get 12-13 drops. If so, then your pool water definitely has high salinity.

The next question is this - how old is your cell? Have you pulled it out recentky to check the plates for scaling? Do these CircuPool SWGs use a separate conductivity probe for salinity? If so, is it in good shape or corroded?

I will try the distilled water test. Good idea.

I just cleaned my cell yesterday. I don’t have any idea how the Circupool measures salinity. I will call them today to find out and ask how accurate they find it to be.

 

[Jimrahbe]

I was thinking about that, making my own calibration solution. Just standard table salt would work?

d,

I would assume so, but that is more of a "Matt" question, as I'm not much of a chemistry guy...

I like Matt's suggestion better, but I did not see it until after I had posted...

Thanks,

Jim R.

 

[dooger54]

d,

I would assume so, but that is more of a "Matt" question, as I'm not much of a chemistry guy...

I like Matt's suggestion better, but I did not see it until after I had posted...

Thanks,

Jim R.

I may try both ways just for fun.

 

[JoyfulNoise]

Making standards only works when you’ve got good measuring equipment - triple-beam balances, graduated flasks, etc. Then, when you make your mix, you have to standardize the standard....just cuz you mixed salt and water doesn’t mean you got the concentration you wanted....

 

[Jimrahbe]

Matt,

I realize it would not be as accurate as an official "standard", but would not mixing salt and water give you something that was +/- a couple of hundred ppm? I think the goal is just to see if his test comes close to what is expected, not dead on...

That said, I like your diluted idea test better..

Jim R.

 

[ping]

How old is the cell?

Have you been adding any salt?

What is the salinity of the pool fill water?

 

[JoyfulNoise]

Matt,

I realize it would not be as accurate as an official "standard", but would not mixing salt and water give you something that was +/- a couple of hundred ppm? I think the goal is just to see if his test comes close to what is expected, not dead on...

That said, I like your diluted idea test better..

Jim R.

Hey Jim,

Just me being my old self. I often had to work with standards and mix up my own standards. Chemistry can be lots of fun when you get to play with the expensive toys. The facility I worked on had both an on-site water treatment plant (18.3 MOhm DI water delivery system to every wet lab) as well as its own waste treatment facility so we could toss pretty much any chemical concoction down the drain and knew it was taken care of. I had autonomy to order pretty much any chemical or piece of equipment needed that was under the capital limit of $2000. If it was a capital item there were a few more hoops to jump through and signatures to get....fun times....

 

[dooger54]

How old is the cell?

Have you been adding any salt?

What is the salinity of the pool fill water?

Cell is about 3 years old.

Have not added any salt since last spring when I did a partial drain and refill to get CYA down.

I have not tested my fill water. I can do that.