Salt readings differ from SWG ProLogic Goldline vs Manual Salt check

[AtriosM3]

Hi TFP Folks!

Appreciate any help on this topic.

MY SETUP:
Pool: 30,000 gal
Hayward ProLogic Goldline Board
Hayward VS Pump (SP3400VSP)
SWG: Optimum Pool Technologies Simple Cell (replacement for Hayward T-Cell-15 Turbo Cell)

Salt - Further Reading

www.troublefreepool.com

Recommended Salt PPM for my system: 2700-3400 (per Hayward manual)

I'm new to the SWG. Just installed the above model. I wanted to try it out vs Hayward's version. We shall see how it does.

The SWG on the ProLogic would initially read 2300-2400 ppm for the Salt level and then a litle while later would show "Very Low Salt" without any further number PPM reading. I understand the reading may not be exact by the science the system may test for the salt level (electric conductivity per this article on TFP).
However, I have an eXact iDip photometer digital reader (eXact iDip® Photometer). This thing is amazing and takes my worries out of reading chemical levels for my pool and hot tub. I know, some may say it's overkill, but it helps me sleep better at night.
The iDip uses a Chloride strip to measure the Chloride and then uses an algorithm to calculate the NaCl (Salt) ppm level. Using my iDip, I am getting 2900-3100 ppm salt (NaCl) readings.

Can anyone explain a little more about the different readings from the SWG and the iDip. I was reading in an article here that muriatic acid ads some chloride by the nature of the compound which can increase the "SALT" level. Also, liquid chlorine comes as "Sodium Hypochlorate" which can possibly add sodium to the water. Can this mess with the readings from the iDip or even the SWG.

In any regard, I am starting to lose sleep over this and would like to figure out if I need to add salt to my pool and how much when taking into account the above information. I would hate to add too much and then need to drain some to level off the salt.

Thank you in advance for your help

 

[PoolStored]

Sooo...let's start with this.

1. The only real thing that matters is whether or not the cell is happy. If it registers a salt level that it is happy with, and makes chlorine, you are golden.
2. Photometry is not very accurate for salt testing. If you want to sleep at night get the Taylor K-1766 salt drop test kit, it is the gold standard. Yes, even better than anything you can get for a couple hundred bucks that is an electronic tester.
3. Us the 1766 to know the true salt value that makes your cell happy. Cells can be +/-500 off from actual from the 1766. Cell says 3000 and is happy, but Taylor says 2800? Maintain 2800 using the taylor and you are golden.

muriatic acid ads some chloride by the nature of the compound which can increase the "SALT" level. Also, liquid chlorine comes as "Sodium Hypochlorate" which can possibly add sodium to the water.

Muriatic acid will not add salt. Liquid chlorine adds salt, but 1 gallon of the average liquid chlorine will add 5.7ppm of salt.

 

[AtriosM3]

Sooo...let's start with this.

1. The only real thing that matters is whether or not the cell is happy. If it registers a salt level that it is happy with, and makes chlorine, you are golden.
2. Photometry is not very accurate for salt testing. If you want to sleep at night get the Taylor K-1766 salt drop test kit, it is the gold standard. Yes, even better than anything you can get for a couple hundred bucks that is an electronic tester.
3. Us the 1766 to know the true salt value that makes your cell happy. Cells can be +/-500 off from actual from the 1766. Cell says 3000 and is happy, but Taylor says 2800? Maintain 2800 using the taylor and you are golden.

Muriatic acid will not add salt. Liquid chlorine adds salt, but 1 gallon of the average liquid chlorine will add 5.7ppm of salt.

OMG So the Taylor K-1766 salt drop test kit out does a photometer?!?! That's nuts! Can you explain why the K-1766 would be better than the photometer? Would love to hear the science as to why. I love science and knowing logic behind things. I appreciate the feedback.

But that is a bummer that being true. Dang... : (

 

[PoolStored]

Has anyone tried the Exact iDip photometer.

Just wondering if anyone is using this and what they think of it. https://sensafe.com/exact-idip/

www.troublefreepool.com

 

[AtriosM3]

Sooo...let's start with this.

1. The only real thing that matters is whether or not the cell is happy. If it registers a salt level that it is happy with, and makes chlorine, you are golden.
2. Photometry is not very accurate for salt testing. If you want to sleep at night get the Taylor K-1766 salt drop test kit, it is the gold standard. Yes, even better than anything you can get for a couple hundred bucks that is an electronic tester.
3. Us the 1766 to know the true salt value that makes your cell happy. Cells can be +/-500 off from actual from the 1766. Cell says 3000 and is happy, but Taylor says 2800? Maintain 2800 using the taylor and you are golden.

Muriatic acid will not add salt. Liquid chlorine adds salt, but 1 gallon of the average liquid chlorine will add 5.7ppm of salt.

Has anyone tried the Exact iDip photometer.

Just wondering if anyone is using this and what they think of it. https://sensafe.com/exact-idip/

www.troublefreepool.com

Thanks.

I have ordered the Taylor K-1766 salt drop test kit. Thank you for the recommendation and advice. I will report the difference between the photometer and the kit. I'm curious to see how they fair.

 

[PoolStored]

I have ordered the Taylor K-1766 salt drop test kit. Thank you for the recommendation and advice. I will report the difference between the photometer and the kit. I'm curious to see how they fair.

Me too. I have not had a situation (1000s of pools helped), nor have I seen (100s of thousands of pools helped) on TFP, where the drop tests have failed to be accurate (barring un-expired reagents). I have seen LOTS of threads where members rely on technology (spin testers, electronic testers, photometry testers, ColorQ) utterly fail. I might recommend, especially with the salt test, that you acquire a spin stir. Doesn't matter the brand or source. This is one test that the spin stir really makes it accurate and reliable. I trust the drop test an the stir...I sleep well at night.

Smart Stir Magnetic Stirring Device

tftestkits.net

Amazon.com

 

[Mdragger88]

Is your cell size set to t15?
Also, how long has the cell been in?
This may help

Hayward ProLogic - Further Reading

www.troublefreepool.com

 

[ajw22]

I understand the reading may not be exact by the science the system may test for the salt level (electric conductivity per this article on TFP).

The Hayward system does not have a conductivity sensor. It approximates the salt level using a calculation, and not any measurements, using the volts and amps based off the performance of a new Hayward cell.

You already introduce an unknown variance into the equation using a clone cell that we do not know how well it mimics a Hayward cell.

So you have two systems each using an algorithm to estimate salt level and no direct measurements of actual salt levels. The K-1766 will give you a direct chemical measurement of the salt level.

For more on how Hayward systems determine salinity read Hayward Aquarite SWG - Further Reading

 

[Bob Jakob]

Generic salt cells are notorious for incorrect salt readings.

 

[AtriosM3]

Me too. I have not had a situation (1000s of pools helped), nor have I seen (100s of thousands of pools helped) on TFP, where the drop tests have failed to be accurate (barring un-expired reagents). I have seen LOTS of threads where members rely on technology (spin testers, electronic testers, photometry testers, ColorQ) utterly fail. I might recommend, especially with the salt test, that you acquire a spin stir. Doesn't matter the brand or source. This is one test that the spin stir really makes it accurate and reliable. I trust the drop test an the stir...I sleep well at night.

Smart Stir Magnetic Stirring Device

tftestkits.net

Amazon.com

Thank you, sir! I ordered the Taylor kit and also the spin stir so I too can sleep well at night

Just got them both (Tayler salt test kit and spin stir) and tired them out. So here are the results.

Readings below are in NaCl ppm.

Taylor

• Pool: 2800 ppm
• Hot tub: 3200 ppm

iDip Photometer

• Pool: 3320 ppm
• Hot tub: 3960 ppm

To me, there are significant differences. I did call iDip (Water Quality Experts | Industrial Test Systems) to see if they had any thoughts on this. However, I didn't get much info from them on the differences. But the guy I spoke with did give me a good idea to check out. He mentioned sending a sample to an independent lab to get tested. Now I know this sounds like OCD, but I'm thinking about doing this for informational purposes. I'll report back once I get a chance to do it and if it doesn't break the bank

Is your cell size set to t15?
Also, how long has the cell been in?
This may help

Hayward ProLogic - Further Reading

www.troublefreepool.com

Yes, it's set to T-15. However, I was reading on one of the threads that you can possibly set it to T-9 to overcome the low salt reading. Does anyone have any experience or info on that? Will anything change with the chlorine production if I change the cell size to T-9 instead?

The Hayward system does not have a conductivity sensor. It approximates the salt level using a calculation, and not any measurements, using the volts and amps based off the performance of a new Hayward cell.

You already introduce an unknown variance into the equation using a clone cell that we do not know how well it mimics a Hayward cell.

So you have two systems each using an algorithm to estimate salt level and no direct measurements of actual salt levels. The K-1766 will give you a direct chemical measurement of the salt level.

For more on how Hayward systems determine salinity read Hayward Aquarite SWG - Further Reading

Thank you for the reading material. Very informative. Nothing like nerding out with some late-night TFP pool reading

Generic salt cells are notorious for incorrect salt readings.

I figured and thought I'd try to see where my luck was with this. It's working at the moment as I did at more salt. Now it's registering at 2500 ppm salt level on the ProLogic, but the actual salt level is at 2800 ppm per the Taylor kit. That shouldn't impact the performance of the salt cell?

 

[ajw22]

If the cell is happy and producing chlorine then your salt level is good. You are over analyzing minor differences and error rates in the differing methods used to measure salt.

A 500 ppm difference in the salt measurement of your pool is within the +/- error range of the testing.

The 760 ppm difference in your spa measurement is a bit higher but I would not base any conclusions on one data point. You could have sampling errors. Your spa water may not be well mixed and homogenous.

There are many ways errors can be introduced into the water testing process. For the salt test accuracy is +/- 500 ppm which is a wide range.

Sending a sample to an independent laboratory will prove nothing.

If you want to calibrate your various testing methods the first thing you should do is mix up a standard solution of a known ppm. The first test is how accurate can you make the standard solution using distilled water and pure salt. What errors are introduced in that mix by a lack of salt purity?

Then do 100 tests on the standard solution you created and see what the range of accuracy you get. And send the calibrated solution off to that independent laboratory and see how their testing differs.

Only then may you have an understanding of the range of repeatable results and variability in the testing methods.

How this will all help you with your pool care I do not know.

 

[rongawer]

OMG So the Taylor K-1766 salt drop test kit out does a photometer?!?! That's nuts! Can you explain why the K-1766 would be better than the photometer? Would love to hear the science as to why. I love science and knowing logic behind things. I appreciate the feedback.

But that is a bummer that being true. Dang... : (

You were correct in your first thinking. Photometers such as eXact iDip, Hanna Checker, or Hach Photometers make have stated accuracies depending on the parameter being tested and dependent on the reagent used and tend to range from 5% to 10%. Considering the variabilities of a drop test, photometers are generally more accurate, but even more so - have a much higher resolution. However they also require accurate measurement of the sample, normally using a pipette or syringe. Stating that they are digital strip readers is a misrepresentation as they don't read strips, but rather use photometric analysis of reagent that is mixed in either a specific volume cuvette or, in the case of the iDip, a 4 ml cell.