Hayward salt reading increasing as temperature goes down

[ned8377]

We've had some cool weather here recently and pool is now 76 - was 84 last week. Is it normal for average and instant salt readings to increase slightly as the water cools down? They've increased about 150 ppm since last week. I understand that, with Aqua Rite, temperature is a factor in how much salt it thinks is in the pool. If this is true then I definitely don't need to be adding any salt in September.

 

[jblizzle]

The reading in the SWG is +/-400ppm ... I would not sweat a 150ppm difference.

 

[ned8377]

It is not a difference between my testing and the SWG but is the reading from the SWG. It has gone up about 150 ppm since it got cooler. No one has put salt in the pool.

 

[jblizzle]

Again

The reading in the SWG is +/-400ppm ... I would not sweat a 150ppm difference change.

Still within the noise of the SWG salt readying accuracy.

 

[JamesW]

Also note that evaporation can cause a salt level increase. And I don't think the unit reports anything other than even hundreds. So I'm not sure how you're getting a 150 difference. In any case, as already noted, it's well within the accuracy/resolution of the measurements.

 

[pooldv]

You definitely don't need to add any salt unless the SWG stops making chlorine and says to add some salt. The salt test is just meant to be a sanity check from ti e to time because as SWG cells get old they report larger and larger differences from reality and you don't want to end up with the SWG reporting 3400 ppm but you really have 5000 ppm in the pool. This isn't a +/- a few hundred checkpoint, more like +/- 800-1000 checkpoint. Salt level is not that critical. For my SWG the manual says 2800-4500 ppm salt is fine, with 3200-3400 being ideal I think.

Be careful when water temps drop below 65 or so because the SWG will report false salt errors and/or stop making chlorine. I found that out the hard way in year one and ended up with salt above 4500 ppm. I don't close our pool and I switch to bleach as soon as the chlorine level starts to drop or the SWG starts acting weird. During non-swim season I use bleach to keep the chlorine level right at 10 ppm, 15 if I'm not going to be able to add bleach for a while.

 

[ned8377]

Thanks for all the help everyone but my question was really this: Does temperature of the water affect the level of salt that the Aqua Rite reports? I'm not talking about below 60 degrees or 50 degrees but just say 84 down to 76. I haven't had evaporation since there has been light rain and slight dilution of the salt mixture and there has been no drainage from the pool due to overflow. When I said it had increased by 150 ppm, that was just an average of the increase I have seen. Thanks!

 

[jblizzle]

YES the temp will affect the salt reading. The SWG does not measure the salt level ... based on the water temp and conductivity of the water it estimates the salt level.