Calcium & Salt


LifeTime Supporter

We have hard water in our area and I have been told by our PB that we should expect to drain our pool every 3 to 4 years to keep the calcium under control.

As I am considering using a stone on the raised bond beam -- calcium build-up concerns me greatly. I love the look, but don't want to buy a maintenance headache.

Will a Salt pool 'soften' the water / lower the calcium in the water? If so -- how does this work -- does the calcium in the water precipitate out? How low will the SWG get the CH?


chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
The CH will only get lowered via dilution with water that is lower in CH than the water it is replacing. There are Calcium reducing/sequestering products that lower its effective concentration, but you don't have to completely drain your pool to deal with this. You can simply to partial drain/refill every so often or even use winter rains to overflow the pool (assuming it doesn't freeze over which it had better not near San Diego!). In fact, in the past I've used winter rains to dilute my pool water though I haven't done that the past couple of years since I wanted to try out a higher (1000-1500 ppm) salt level to see if my wife noticed any difference.

What is the CH of your fill water? If you get a pool cover to prevent evaporation, then that will significantly reduce the rate of rise in CH from evaporation/refill.

An SWG will not reduce the CH in the pool. You'd have the same problems with CH in an SWG pool as with your current situation. In fact, high CH is a bigger problem with an SWG pool since higher saturation index conditions tend to cause more scaling in the SWG cell (one of the SWG plates produces a very high pH near the plate -- the polarity of the plates is reversed every so often, but in the meantime scale can build up).



LifeTime Supporter
Thanks - -I guess everything i read about SWG is not true -- that's why I come here. I think the fill water is 120-150 but San Diego has just sent out notices that they will be getting a different 'mix' of water that will be a lot harder. Who knows how hard.

If SWG does not help -- I am having second thoughts about a rough (stone) surface on the raised bond beam. I picture spash-marks -- white stains mostly near the water-line and then decreasing as it gets to the top (24" high). Maybe I'm just letting my imagination get to me...

I have a spillway that will free-fall 24" (36" wide). Will this effect the chamicals and how much more evaporation will I get (increasing CH) with this over a simple tile 'run-down-the-face" spillway?

i wish there was a way to chlorinate the spa without having the spill-over on at all -- but I'm afraid of sucking the spa dry if I use the bottom drains in the spa instead of the spillway. If I could do this I could eliminate a lot of splash-back (and noise at night).

I have been told that within the next 2 years San Diego will go to time-of-use electricity metering. This will make me want to run the pump at night (good-bye solar) -- and I'd like to find a way to quiet the spill in the sleeping hours.

---=== Appoligies for the sumjest change -- I know this is 'testing the water' I just got going. ===---

Many thanks