Calcium Hardness is always high

Aqua Woman

Member
Jul 31, 2019
6
Lake Charles, LA
First time post, patience, please. We have owned our pool a bit over a year,and I finally decided to take charge of things myself because the pool store was getting nowhere. I ordered the TF 100 kit and have started using the PoolMath app. My issue is how fast my pH drifts into alkaline territory (above 8.3) Pool folks blamed the hardness, drained half the water in the pool, then refilled it. Same issue as before. My latest tests are: pH 7.2 (I'd added a gallon Muriatic Acid yesterday), FC 3.5, CC 0, TA 90, CH 900
I tested the source water (from the hose we use to fill the pool), and pH 7.8, TA 300, CH 175
So, what's going on? We do use the natural gas heater about 4 hours a week. Filter cartridge and saltwater generator were just cleaned. I'm most worried about where the calcium is coming from. My water is clear (always has been), and is very nice to swim in (can open your eyes under water). Do I worry about the CH? The pool rep said due to almost zero exposure to the sun(Roof over the pool) use no CYA. I'm also questioning his advice on that.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
21,937
Laughlin, NV
Welcome to the forum!
There are only two ways your CH increased above your fill water CH, you add water due to evaporation, or you add calcium via calcium chloride or calcium hypochlorite. Have you added either of those products? How much evaporation loss do you have from the pool?

You should have at least 30 ppm CYA in your water. With it getting minimal UV exposure, that should be sufficient to make the chlorine less harsh.

Your pH rises due to your high TA fill water. You will have to continually add acid when you use fill water.
I suggest you read ABC's of Pool Water Chemistry.
 

Aqua Woman

Member
Jul 31, 2019
6
Lake Charles, LA
Thanks for the input. I have spent a lot of time reading just about everything I can including the ABCs. I add about 8 inches of water once a month due to evaporation. When the pool was first built OVER a year ago, the pool folks cranked up the SWG and put some type of chlorine tablets in the skimmer basket. When I brought in a sample after a few days, the free chlorine was in the teens!! So, pool guys drained half the water, then refilled without adding anything but salt. The SWG alone has kept up very well with the FC since. The only other thing I ever added (three times earlier this summer) was non-chlorine shock. Once I discovered TFP, I don't do any of that anymore either. So, does that sound like my fill water is causing such a high CH? I will adjust the CYA up.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
21,937
Laughlin, NV
If you get 8 inches of evaporation a month that will raise your CH over time. The calcium stay in the pool when the water evaporates. The fill water then adds more calcium.

I would think you get rain to refill your pool at times. Rain water does not contain calcium.
 

Aqua Woman

Member
Jul 31, 2019
6
Lake Charles, LA
That explains it, I guess. Sure seems to have gotten very high in just a few months. I didn't add water all winter. We have an indoor/outdoor pool, in a sense. It is in a screened room with a metal roof (mosquitoes). And we use our heater often. Thanks for the insight. Never thought about no rainwater......any ideas about getting around the problem of no rainwater?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
21,937
Laughlin, NV
If you can collect rain water to use as fill water that will relieve your CH rise.

I am surprised the CH is rising that quickly. My CH triples in a year, but we have large evaporation rates and no rain.
 

Aqua Woman

Member
Jul 31, 2019
6
Lake Charles, LA
Yeah, that's what's had me concerned. But I'm beginning to think that when the pool guys overdid chlorine with those pucks, they overdid the calcium also, and a half drain and refill didn't put enough of a dent in it. What does "harsh" chlorine feel like? The water has always felt fine, only once (when the pool guys overdid it with the pucks) did it bleach anybody's suit. We swim with our eyes open, there is no smell, skin seems ok. What if I keep the chlorine around 1.0? Still too much? Swim season is almost over and I hesitate adding something at the end of the season.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
21,937
Laughlin, NV
Harsh chlorine is like a public pool. No CYA and 1 ppm or so FC. You fell like you need a shower after swimming and your skin is itchy or dry. Eye irritation is due to low pH or CC. Not FC.

I would get 30 ppm CYA in this water and keep the FC at a minimum 3 ppm. target 4-5 ppm. Your SWCG should have no issues maintaining that with the covered pool.

Pucks do not add calcium. They add CYA. If anyone used powdered chlorine, it could have been cal hypo.