Salt buildup over time with chlorine

Jun 20, 2012
104
My 15KGal pool is about 6 months old. I stopped using pucks when the CYA got up to 50 and now pour chlorine in about every two days. At some point I will likely have to leave town for one or two weeks so I need to automate. I have some Luederstone coping in an area where there would be splashout so am concerned about salt damage to the stone. (The rest of the areas where there would be splashout is concrete covered with Sundek and I haven't read about any salt issues with Sundek here at TFP.) I've read that over time chlorine will add salt and it can only be removed via draining. Since I live near Austin, I won't be draining my pool seasonally. Therefore my salt level is eventually going to get higher and higher with chlorine injection. That seems to be a downside of automated chlorine injection while with a SWG the level would consistently be about 3400 ppm. It seems in either case (injection vs SWG) I will need to seal the Luederstone and since the SWG is more (not totally) hands off (no need to haul chlorine) that seems to be the way to go. Is there more information I need to decide concerning injection vs SWG? (I can do the Liquidator vs pump investigation later.)
 
Chlorine will slowly raise the salt level, but splash out (and backwashing) will slowly lower the salt level. In almost all cases this balance reaches equilibrium well below the salt level used with SWG. The worst case for salt levels are when you have a cartridge filter, don't winterize, and almost never swim. In those situations the salt level can eventually get fairly high, but that process takes years and years, long enough that a little intentional water replacement is not a big deal.
 
Thanks JL, Do you have any information about the level of salt at which would I need to start to be concerned about my Luederstone?

Also, at first I was thinking about adding salt to remedy the dry skin effect, but I might just wait for the salt from the chlorine to do that naturally. Is there information on the rate of salt build up when using chlorine (8.25% these days).
 
Using the bottom of the poolcalculator.com, 1 gallon of 6% bleach will add 6.8ppm of salt. 1 gallon of 10% will add 11ppm of salt ... so 1 gallon of 8.25% likely adds around 9 ppm of salt to your 15k gallon pool.
 
To give you a real world example, since draining my pool and starting fresh three years ago, I've used only liquid chlorine and last summer when I took a sample of my water to Leslie's (to see how their test stacked up to mine), their test showed my salt level to be at 1500ppm**, which is well below that of a typical SWG pool. I have a DE filter, and three kids splashing water out all Summer so I end up replacing a decent amount of water every year.


**Of course the Leslie's test results were off by quite a bit when it came to FC, PH, and CYA levels, so I don't really know how close their salt measurement was.
 
Thanks all. So it seems like salt is not an issue with chlorine without an SWG, i.e. I shouldn't have to worry about my Luederstone using chlorine vs SWG. So now I just have to decide on how automate, i.e. peristaltic pump vs SWG plus sealing the Luederstone. I've eliminated the Liquidator because apparently its flow rate is too inconsistent if leaves are an issue. I have a lot of trees in my yard so that is an issue in both the Fall and Spring (due to lots of Live Oaks).
 
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