Salt levels rising

Joey316g · Jul 10, 2016

I have a SWG in my pool system. I opened the pool in late May. Tested the salt level. Was 2200. Added 160 lbs of salt, and the red light cleared on my generator and everything worked fine. Tested again at the point and it was 3400. Ok everything is great. So today I tested it with my monthly testing and it was 4000? I did the test two times and got same number both times. Is this possible? Can the pool gain salt?

JohnT · Jul 10, 2016

If you add chlorine you add salt, so you can see some gain.

Joey316g · Jul 10, 2016

So say if you do a slam for a few days you could see a substantial increase in salt?

JoyfulNoise · Jul 10, 2016

Every gallon of acid added to 10,000 gal if pool water will increase chloride content by 35ppm. A bottle of bleach only contains a few hundred ppm salt so even several gallons of bleach doesn't add that much.

Have you been adding a lot of acid? Also, are you testing actual chloride levels with a K-1766 or relying on your SWGs salinity readout?

Joey316g · Jul 10, 2016

I might have added a gallon and a quarter in the past 7 weeks. Doesn't add up. As it says in my signature, I'm using a Taylor salinity test that came with my kit

JoyfulNoise · Jul 10, 2016

Municipal fill water has salt in it too. You can check your tap water to see how high it is but to do it you should increase the test volume to 40mL so that each drop of titrant is 50ppm salt.

Salt only increases from an input source - bleach, acid, trichlor/dichlor and fill water. Your testing is also, at best, +/-300ppm or so (it's a little worse than +/- 1 drop).

JohnT · Jul 10, 2016

JoyfulNoise said:
Every gallon of acid added to 10,000 gal if pool water will increase chloride content by 35ppm. A bottle of bleach only contains a few hundred ppm salt so even several gallons of bleach doesn't add that much.

Have you been adding a lot of acid? Also, are you testing actual chloride levels with a K-1766 or relying on your SWGs salinity readout?

A gallon of bleach adds much more salt than that. After it is used up you'll see 10-20ppm increase in 10,000 gallons of water per gallon of liquid added depending on the strength.. Probably wouldn't account for 600ppm in this situation, but it can make a significant difference over time.