Recalibrate IC40?

Saturn94

Bronze Supporter
Mar 11, 2015
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SE Virginia
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SWG Type
Hayward Aqua Rite (T-15)
Sorry you’ve had issues. But I’ve used that kit for years and it’s spot on accurate. I’ve even measured homemade standard solutions and it comes well within testing error limit. The chemistry behind the test is very simple so there’s not much that can go wrong. Perhaps there’s something in your water interfering but it’s hard to say. I’m not a huge fan of Hayward cell salinity measuring methodology as it uses the cell itself to act as conductivity probe. That can be fraught with difficulty as it assumes all cells are the same and infers EC based on cell electrical parameters. Not a good assumption to make. That said, none of the manufacturers do a very good job on salinity measurement so you have to take what you get.

Meters are not foolproof. Even if they are calibrated against a standard, it still isn’t going to give accurate results because pool water has lots of dissolved ions in it. That is going to produce an offset in the measurement that you can’t account for easily. So, in the end, it’s no better than using the SWG because you really have no way of knowing how the EC value compares to the true chloride content of the water. The K-1766 measures chloride content exactly.

Hope you get it sorted out. And, on the bright side, you have a spare cell. Or, maybe you can come up with a creative way to run both cells in parallel and then halve your pump run time.

I understand your point about the chemistry using the K1766 vs the reliability of meters.

So where does this leave an average pool owner like me when trying to figure out if a new cell is needed?

I followed the standard advice here using the K1766 results compared to the old T15 cell salt readings, which lead to buying a new cell. But when the new cell resulted in the same results as the old cell, I had the cells tested (both passed no problem). I had the store that tested the cells also check the salt level (they used some kind of electronic meter) and their result was in close agreement with what my SWCG is reporting.

So what do I do going forward? Just feed the SWCG when it reads low as long as it’s producing adequate FC, and just have the cell tested if I suspect it’s dying? Worse case, when the existing cell proves dead, this may result in high salt warning with a new cell, requiring some water replacement/rebalancing a few chems.

If I just rely on the K1766 to tell me when to replace a cell, then I risk the situation buying an expensive new cell unnecessarily. 🙄

You mentioned something in the water possibly causing an interference. Anything in this list stand out as a possible source of interference?

City water/rain
68% Cal Hypo (LC was in short supply at opening, I don’t normally add calcium, so CA level is usually below 100)
10% liquid chlorine (normally use at opening, and once in a great while to bump up FC if needed)
Water softener salt (no additives)
100% CYA (70-80ppm)
Borax (used to raise pH at opening)
Boric Acid (50ppm)
Washing Soda (used at opening to raise pH and TA)
Jack’s Magic Purple Stuff (2qts at opening, approx 12oz weekly for iron stain control. Using a Taylor drop test recently, phosphate measured 2000ppb)

My apologies to the OP for sidetracking this thread. Perhaps this discussion should be continued in my SWCG thread (Moderator, please advise)?

Thank you. 😀
 
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Saturn94

Bronze Supporter
Mar 11, 2015
1,299
SE Virginia
Pool Size
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Chlorine
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SWG Type
Hayward Aqua Rite (T-15)
The proper way to verify reagents in any titration test is to first standardize your reagents against a known laboratory standard. You mix up the standard solution, you test your reagents against that and then you either decide if your reagents are too far off (maybe they sat on the shelf too long) or you calculate a correction factor to them (maybe fresh they were 100ppm/drop but now they are 95ppm/drop). You NEVER standardize one test with unknowns against another test with unknowns, that’s not correct lab practice.

In this case, it would be fairly easy to check the reagents of the K-1766. If you have a precise enough scale, you can make a standardized salt solution out of DI water and non-iodized table salt. If that’s too tricky to do, you can buy a standard salinity solution online and test the kit against that. There are plenty of standard salinity solutions you can buy very cheaply. If the reagents then test against a known standard and are within an acceptable error margin, then the issue isn’t with the K-1766.

I received my salt calibration solution (3000ppm) and tested it with my K1766. The K1766 result was 3400 (checked twice). It’s my understanding that the K1766 is suppose to be accurate within 200ppm.

As to not further derail this thread, I’ll continue this discussion and other test results in my SWCG thread here


I would love to hear from our experts here in my SWCG thread. Thanks! 😃
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
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Tucson, AZ
Pool Size
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Plaster
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Pentair Intellichlor IC-60
I received my salt calibration solution (3000ppm) and tested it with my K1766. The K1766 result was 3400 (checked twice). It’s my understanding that the K1766 is suppose to be accurate within 200ppm.

As to not further derail this thread, I’ll continue this discussion and other test results in my SWCG thread here


I would love to hear from our experts here in my SWCG thread. Thanks! 😃
Are you using a SpeedStir?
 

Saturn94

Bronze Supporter
Mar 11, 2015
1,299
SE Virginia
Pool Size
20000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Are you using a SpeedStir?

No. I do make sure to mix thoroughly between drops as I know rushing the drops and not mixing thoroughly between drops can result in a false high reading. I also noticed in this Taylor video they do not use a SpeedStir.


I’m confident I’m swirling/mixing very well, certainly better than the guy in the video demonstration.

PS - I posted more about this in my SWCG thread.
 
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