Salt reading vs temperature

lborne · Nov 30, 2009

How will the temperature affect the salt level reading?

My SWG was showing 3500 ppm salt about 2 weeks ago when the temps were 76-78. This week, the temp is down to 67 and the salt level reading is 3000. There has been no water change, rain, splash out, etc. I can't think of any way salt was removed.

The SWG reads both salt and water temp, so I thought it would self correct.

mas985 · Nov 30, 2009

lborne said:
How will the temperature affect the salt level reading?

My SWG was showing 3500 ppm salt about 2 weeks ago when the temps were 76-78. This week, the temp is down to 67 and the salt level reading is 3000. There has been no water change, rain, splash out, etc. I can't think of any way salt was removed.

The SWG reads both salt and water temp, so I thought it would self correct.

Most SWGs these days will compensate the salt readings for temperature so it should stay constant but it depends on your brand. Mine stays within +- 100 ppm over temperature. What brand is your SWG?

lborne · Nov 30, 2009

I have a Compu Pool CPSC 26. Not much info out there on them.

polyvue · Nov 30, 2009

lborne said:
I have a Compu Pool CPSC 26. Not much info out there on them.

I was able to locate an Owner's manual; it doesn't directly address why the salt level would change suddenly but it does explain how the unit works in some detail. If the first link doesn't apply to your model, check out the second link -- the manufacturer's web site.

http://www.compupool.com.au/pdf/CPSC%20 ... Manual.pdf

http://www.compupool.com.au/index.html

Strannik · Nov 30, 2009

i thought they only have indicators for high/low salt, not the actual read out?

lborne · Dec 1, 2009

Yes there are indicators, but when first turned on, and every few hours it seems, it checks the salt level and temperature and displays it for a while. Then it reverts back to showing the output level and you can use the select button to see the salt and temp again.

Anyway, I still can't figure out if I've somehow lost salt, or if the colder temps could affect the salt concentration readings. I know lower temp lowers conductivity, but not sure if this unit compensates.

PaulR · Dec 2, 2009

Speaking without the benefit of experience... A difference of 500 seems like not worth worrying about too much, but worth keeping an eye on. I'd monitor salt and temp for a while; if they seem to track, then the unit isn't compensating for temp, and that's not a big deal. If they don't track, then it's worth thinking about what else might be going on.
--paulr

Strannik · Dec 2, 2009

test it with the strips
i'm not sure how reliable their salt meter is

mas985 · Dec 2, 2009

lborne said:
How will the temperature affect the salt level reading?

My SWG was showing 3500 ppm salt about 2 weeks ago when the temps were 76-78. This week, the temp is down to 67 and the salt level reading is 3000. There has been no water change, rain, splash out, etc. I can't think of any way salt was removed.

The SWG reads both salt and water temp, so I thought it would self correct.

Another option is if your SWG is plumbed for the spa as well, heat up the spa and see if the salt reading changes. You may need to use the instaneous salt reading if the unit has one since some units average the salt reading over a couple of cycles.