sudden jump in salt reading

[Jim H]

In my experience over the past 2 years, one bag of salt seems to increase my levels by 200-300.
My levels last week were at 2800. added two bags and a few days later its at 3200. added another bag and a few days later its 3600. Cool.
Just happened to check levels this weekend (3 more days later) and its reading 12000.
I waited a few days between adding bags- should I have waited longer?
THis is the way I have added salt for the past 2 years and never encountered this problem.
The SWG is only 2 years old, but from reading these posts even if it was failing it would tend to read too low, not too high.
I haven't bothered to check it against any other store bought salt checkers because everywhere I read on these posts they are unreliable.
So I can't come to terms with this mysterious jump of 9000 on the salt level.
I let the pump run all day, shut off for the night as always, and rechecked this morning and still the same reading.
I am in the process of draining my pool 1/2way then refilling it. I'm hoping that this will answer my question as to whether the levels are truly that high or its a faulty sensor because if it is still reading the same after I do this I know there is something fishy. Any other ideas that are not as time consuming and costly?

 

[Jim H]

Don't know if it matters in this case, but I know everyone likes to know the other readings so just in case it makes a difference:
FC 5 pH 7.5 TA 90 CH 250 CYA 70
Everything was perfect...and now it'll all get screwed up with the emptying a refilling. Frustrating.

 

[BattleOfYakima]

To confirm, all these salt measurements came from the SWG's display, correct?

No Aqua Chek Salt Strips or K-1766 Taylor Salt Test? (Both TFP preferred to SWG reading)

 

[Jim H]

Yes that is correct I was going to pick up one of these things but of the thread say they're not accurate

- - - Updated - - -

I'm surprised these are TFP preferred unless I was looking at the wrong threads everywhere I read before saying SWG device is pretty accurate

 

[BestJoeyEver]

I'm surprised these are TFP preferred unless I was looking at the wrong threads everywhere I read before saying SWG device is pretty accurate

Well sure, your SWG is fine for checking on a regular basis, unless you're suddenly experiencing a *9000* PPM jump! Then you kind of need an alternative to compare to. Even if you buys strips that aren't 'the most accurate' they should still have less than a 9000ppm margin of error right? I'd definitely buy a pack of strips before paying to refill half my pool. Even the Taylor kit would be cheaper. Personally I use an electronic salinity tester because my cell doesn't provide a read out. $100 well spent.

Joey

 

[Jim H]

Well sure, your SWG is fine for checking on a regular basis, unless you're suddenly experiencing a *9000* PPM jump! Then you kind of need an alternative to compare to. Even if you buys strips that aren't 'the most accurate' they should still have less than a 9000ppm margin of error right? I'd definitely buy a pack of strips before paying to refill half my pool. Even the Taylor kit would be cheaper. Personally I use an electronic salinity tester because my cell doesn't provide a read out. $100 well spent.

Joey

Yeah yeah yeah I get it. I'm on my way to the pool store now to buy some.

 

[Jim H]

So the verdict is. Pool store says 3000 and strips say 2800 so it seems like the sensor is on the fritz. Time to call the pool company at least it's still under warranty

 

[ping]

By chance did you add the salt while the SWG was on?

 

[JamesW]

https://images.inyopools.com/cloud/documents/jandy-aqua-pure-error-codes.pdf

Most likely a bad sensor or board. The above link has the test procedure.

 

[Jim H]

By chance did you add the salt while the SWG was on?

I don't recall but quite possible...Am I not supposed to have the SWG running when adding salt? That's a new one to me!

- - - Updated - - -

https://images.inyopools.com/cloud/documents/jandy-aqua-pure-error-codes.pdf

Most likely a bad sensor or board. The above link has the test procedure.

Thanks for the info.

 

[mknauss]

I don't recall but quite possible...Am I not supposed to have the SWG running when adding salt? That's a new one to me!

In the Pentair manual for their SWCG it is specifically pointed out not to run the SWCG when dissolving the salt and waiting 24 hours after adding, with circulation, before starting the SWCG.

High salinity (greater than 10000 parts or so) can damage the SWCG if it is running.

Take care.

 

[ping]

Never add salt to water while a SWG is on, the high salt surge can damage the system.

Most, if not all manuals have that warning.

 

[Jim H]

lesson learned

 

[JoyfulNoise]

Just to close the loop on testing -

- Strips are the least accurate and can be off by as much as 500ppm.
- SWG's are just glorified electronic TDS meters and, even then, are not very good at it. They can be off as much as 400ppm from true.
- The K-1766 is the only way to chemically measure chloride ion levels. It is a chemistry-based test which means it's results are highly accurate since it is only sensitive to chloride ion (Cl-). The way the standard test is laid out (10mL water sample), you get an accuracy of +/-200ppm. If you use a 20mL water sample, you get +/-100ppm accuracy.

That said, the K-1766 should be used to determine your water's exact chloride level. If the SWG matches it or is close enough and satisfied (generating chlorine), then there is no need whatsoever to add salt. If the value reported by your SWG is significantly lower than the actual value, then that typically indicates an SWG that either has scale on the plates or the plates are starting to fail. If the SWG reads a lot higher than the actual value, then it's possible you have a sensor failure (either internal temperature thermistor or a failure of the conductivity sensor).

 

[BattleOfYakima]

Awesome summary post! That's going to get quoted a lot! Thank you!