High Calcium Hardness - Well Water

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Rwhite692

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May 3, 2011
54
Hello, I did a search for this but didn't find anything like my situation...

Just received my Taylor test kit (first "real" test kit I've had in 13 yrs of pool ownership) and tested my Calcium Hardness. It is very high, 460 ppm.

Pool size is 38,500 gallons. I have a little bit of hard water staining at the water line but nothing terrible. Other than Calcium Hardness, I have no other water problems/issues.

On our property, we only have well water. I do have a domestic water softener for the home plumbing. The pool is normally re-filled (to make up for backwashing, evaporation) from straight well water tap, at the pool pad.

Is it worth it to try and replace some of the pool water using the domestic "softened" water? Or is there a better / easier way to reduce my Calcium Hardness?
 
You can get by for one, maybe two pool seasons with CH that high, at which point you either need to replace most of your water or get an RO treatment. You can compensate for high CH levels by lowering PH and TA. How much you need to lower PH and TA depends on just how high CH gets.

You can use softened water, but keep in mind that means lots of recharge cycles for the water softener.
 
The CH level in the pool is going to go up. Any water that evaporates leaves it's calcium behind, so calcium will accumulate in the pool. How fast it goes up depends on how dry a climate you live in. Low humidity means more evaporation, means CH goes up more quickly.
 
Ah, I see. Makes sense. Here in Northern CA it is extremely dry from June through September (it rarely ever rains in those months). So yes we do get a lot of evaporation.

It looks like a partial, perhaps full, water replacement is indeed on the agenda.
 
As shown in this map the evaporation rate in northern California is 50"-60" per year on the coast which is about average because the humidity tends to be around 40% during the day and high at night. It's in the southwest where the evaporation rates can be twice as high. The evaporation rates are even higher if you heat the pool (say, with solar) and keep it uncovered. For an average pool depth of 4.5 feet, this means adding roughly one full pool volume of water to the pool so essentially adding the CH level of the fill water.
 
You might do some checking to see if there are any reverse osmosis outfits that might be able to service your area. Many, many folks in the desert SW use this type of service to keep their hard water in check. Other than that, as Jason mentioned, you can make other adjustments in your chemistry which will allow you to get by with fairly high CH levels. Adjustments in pH and TA are ways that can move your CSI one way or the other to lower the potential for scaling.

Have you given any consideration to having some water trucked in as well? Just trying to explore your avenues here. :)
 
chem geek said:
As shown in this map the evaporation rate in northern California is 50"-60" per year on the coast which is about average because the humidity tends to be around 40% during the day and high at night. It's in the southwest where the evaporation rates can be twice as high. The evaporation rates are even higher if you heat the pool (say, with solar) and keep it uncovered. For an average pool depth of 4.5 feet, this means adding roughly one full pool volume of water to the pool so essentially adding the CH level of the fill water.
Click to expand...


Thanks for posting that, Chem Geek. I am actually located in the Central Valley, about exactly where the "70" label appears. It is way, way drier where I am, vs the coastal / SF Bay areas. And yes, I do keep the pool uncovered, and have a large solar setup...
 
257WbyMag said:
You might do some checking to see if there are any reverse osmosis outfits that might be able to service your area. Many, many folks in the desert SW use this type of service to keep their hard water in check. Other than that, as Jason mentioned, you can make other adjustments in your chemistry which will allow you to get by with fairly high CH levels. Adjustments in pH and TA are ways that can move your CSI one way or the other to lower the potential for scaling.

Have you given any consideration to having some water trucked in as well? Just trying to explore your avenues here. :)
Click to expand...



I think that, as a first step, I may just do a full changeover of the water using my existing water supply.....As I mentioned, I have had no water "problems", other than seeing this high measurement for calcium hardness.

Does a pool with high Calcium Hardness more easily have green algae bloom? If so, I have not had that happen...Just wondering if there are other concerns to be aware of, apart from potential waterline scale, etc?
 
460 isn't all that high!

The only downside to high CH is possible scaling. In over a year since I fired the pool guy I inherited with the house, I've never had CH that low. And in fact, I'm gradually removing scale by keeping CSI in the negatives.

Don't pump out a lot of water just because CH is higher than ideal. Instead, do what I do - use pool water on the lawn, then refill the pool. Every time I do it, my CH goes down 2-3%. A good rainstorm (too late this year) can really drop the CH if you can capture a lot of it. You can test your well water and see what the pH, TA, and CH look like on the fill water. I'm betting TA will be high, and you'll end up needing a lot of acid to get that down so that CSI stays relatively neutral.

Pool Calculator will tell you what your CSI is.
 

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