High Calcium hardness

Singlemalt79

New member
Jun 30, 2019
2
Phoenix
I'm a longtime reader of TFP and I finally decided become a member, buy the K-2006 test kit, and get the Pool Math App. I have a 12,000 gallon, four year old, salt water, pebble pool with pentair equipment and have never had any issues until this past week. Recently I have been getting large amounts of calcium flakes accumulating in the bottom of the pool. Went to the local pool store to get the water tested and they told me I had high nitrates and needed to drain my pool, because the nitrates were eating my chlorine thus causing calcium flakes... After reading many of the threads on this forum I decided to ask you guys for help.

I just did my first pool math test using the aforementioned kit and here's what I have: FC 1.2, PH 7.9, TA 80, CH 650, CYA 80, SALT 3600

I have been adding about 18 oz of muriatic acid (14.5%) every day for the past three days and PH is still high, I believe this is partly responsible for the the calcium flakes. My question is, do I need to drain half the water as pool math suggests to get the calcium level down, or should I concentrate on lowering my PH and boosting the FC to 4 before I drain half the water?

I really don't want to drain my pool, I'm located in the Phoenix area and nightly lows are around 75-80 degrees. I could drain half the pool after sunset and most likely have it filled up before it gets too hot using both mine and my neighbors garden hose. On the other hand everything I have read warns against draining a pebble pool when the temp is above 85 degrees due to possible cracking. Below is a pic of the calcium flakes, I get about this much out of the pool every afternoon. I run a dual speed pump from 10pm to 8am everyday with 4am to 8pm on cleaner mode. I have the IC40 SWG that is set to 65%.

Thank you in advance for any help you can give.


109529
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,397
Laughlin, NV
Welcome to the forum!
Bigger issue is your FC is way too low. Should be a minimum of 4 ppm with a CYA of 80. See FC/CYA Chart
You need to track and manage CSI - Calcium Saturation Index (CSI) - Trouble Free Pool Go to setup in your App and enable CSI. You want to keep your CSI between 0 and -0.3.

You can manage water with a CH of 650. You will need to plan a drain/exchange of the pool volume for this fall/winter.

If you get your TA to 70 and pH kept below 7.5, your CSI will be on the negative side and the calcium scale will decrease.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
Went to the local pool store to get the water tested and they told me I had high nitrates and needed to drain my pool, because the nitrates were eating my chlorine thus causing calcium flakes.
What mumbo jumbo.

Nitrates don't worry me. Algae does. Do you see algae? Is the water clear or murky?

Low FC is worrisome. High CH --and yours isn't all that high for the desert Southwest -- can be dealt with. In fact, your CSI looks pretty good. There's no good reason to drain at the moment. Drop the pH to the lower half of the safe zone and concentrate more on the question of low FC/possible algae.
 

Singlemalt79

New member
Jun 30, 2019
2
Phoenix
Ok I will concetrate on getting my FC up to at least 4 and the PH down to the lower hald of the safe zone. I have enabled CSI on the pool math app and I will be looking into that. I have no algae and the water is crystal clear besides the calcium flakes. Thank you for the advice, I will update you in a few days.