Using a water softener to lower calcium hardness

Lagoony

New member
Oct 17, 2020
2
San Diego
I have a 26,000 gallon plaster pool in San Diego, CA. It's about 2 years old and the calcium hardness has been slowly creeping higher due to evaporation. It's currently at 750 ppm, which is well above the recommendations here. My source water from the tap is about 250 ppm. I've asked around and haven't come across a single person who drains and refills their pool to deal with this issue. A local company that builds and services pools recommends a drain every "5-10 years to deal with old water" which I assume means water that is too high in hardness and CYA. So this leads me to a few different questions..

1. Just how harmful is high calcium hardness? I recently cleaned my Intellichlor IC40 (almost 2 years running without being serviced) and it had scale, but it was less than I expected. I understand that calcium scale will shorten the life of my heater, and contribute to build up along the water line tile. Is that about it? Do I need to worry about the PVC pipes themselves becoming clogged with scale?

2. Based on my water rates, it would cost about $450 to drain the pool and refill with new water (and buy new salt and CYA). Since the incoming water measures at 250 ppm, I'd have to do this about once every 18 months to keep the levels within TFP recommendations. I am loathe to do this, however, since water is a limited resource in these parts, and it just seems like such a waste.

3. I got a quote from one of the water recycling companies that brings a powerful RO filtering system out to your pool to get the hardness down. That would cost me about $1,000 (not including new salt or CYA) with an estimated 15% waste water useage. Although I do care about the environment, the cost difference isn't feasible!

4. I am not terribly familiar with how water softeners work, but one idea I had was to buy one of these stand alone units and then use a pump to force water from the pool through the unit, and do that until I get the hardness down into a reasonable range. The unit I link to below says it will remove 48,000 grains, which I calculate as approximately 31 ppm of calcium hardness in my pool. Does that mean I would then have to backwash and recharge the unit, and then I can do another pass to remove an additional 31 ppm, and continue until I achieve my desired value? Do these things last indefinitely and I can theoretically use the unit for the next 5+ years doing this once a year? If that is the case, it will pay for itself quite quickly and seems like a great solution. I'd love to hear your thoughts on all of the above!! Thanks.

https://www.amazon.com/Aquasure-Har...pY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU&th=1
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
40,929
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
Welcome to TFP! :wave: So your CH is a bit elevated, but still not in a critical range as we have some members who do well with a CH ~1,000 or more. To compensate and keep a healthy "CSI" level (see our PoolMath APP), be sure to keep the pH and TA lower and well managed. CH won't hurt the PVC, but it can accumulate on the pool surfaces and in the SWG cell if the CSI is not controlled.

18-24 months is a fairly common water exchange timeframe for folks in the southwest. Plan for exchanging in the winter when the sun isn't so intense on the plaster.

Not so sure about cycling pool water continuously through the softener since you will encounter regen periods, but softeners are most definitely popular for refills. I myself have a splitter (T-fitting) from my softener to a spigot out back to the pool if needed.

Be sure to visit out Pool Care Basics page and the link below for more info. Enjoy the forum. :swim:

 

Lagoony

New member
Oct 17, 2020
2
San Diego
Thanks for the info! I read further and see that their are some others here who use a softener on their water line (dedicated for the pool) and I will likely go that route, for the future. It sounds like you have a whole house softener and then manually add water to your pool when needed?

My system is currently automated with a float valve for evaporation top-off, but I can add a small softener to that line fairly easily.
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2014
40,929
Texas, San Antonio/Marion, South-Central Area
Pool Size
17888
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-45 Plus
It sounds like you have a whole house softener and then manually add water to your pool when needed?
Correct. If my CH starts to climb too high, I just open the tap (spigot) from my softener to add softened water as needed.
 

Flying Tivo

TFP Guide
Jan 24, 2017
2,796
Monterrey, NL, Mexico
Pool Size
7500
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
If its costing you 450 a year then its feasible to buy a water softener. I have 350ppm city water. I just installed this one Rheem.
And lowered to 25ppm CH. This is a whole house system(in Mx we dont have regulation for separate water lines).

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