Why is Calcium Hardness and CYA falling?

Copernicu

Bronze Supporter
Jul 22, 2020
32
Phoenix, Arizona
For the longest time, my CH was stable at 325. It is now at 275. I have no idea why. And I don't know what, if anything, I should do about it.

Some more info, in case it's relevant:
  • My pool is fiberglass.
  • I am in process of trying to get my TA lowered, so my pH has been on the low side for a while. I am trying to get the TA to about 50 because my pH kept rising and, from what I read, the solution to that is a lower TA.
  • Because my pH is on the low side, my CSI is -0.6 currently
  • I'm in Arizona and it's super hot. But last summer was even hotter and CH didn't fall.
I would appreciate any advice on this.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
47,255
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Only way CH falls is to remove water from the pool and put lower CH water into the pool.

Are you using softened water for make up water?
 

Copernicu

Bronze Supporter
Jul 22, 2020
32
Phoenix, Arizona
My CYA isn't stable (haha), it keeps falling. I'm in Arizona and I'm trying to keep it at 50.

I need to add CYA every week or two. And that's even with me supplementing liquid chlorine with tabs (mainly for the purpose of trying to keep CYA stable).

I haven't figured this out from the other posts I've read. It seems like it's falling faster than it should.

Please help.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
47,255
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
With your CH falling post, I suspect you have a water leak. Lets combine these threads.
 

Copernicu

Bronze Supporter
Jul 22, 2020
32
Phoenix, Arizona
No, just regular city water.

I thought maybe it's interpretation error, as I'm always unsure of the point of when to consider it blue (and not purple). I try to use the method of continuing to put in drops until I don't perceive a change in the color. But 325 to 275 is a 2 drop difference.
 

Copernicu

Bronze Supporter
Jul 22, 2020
32
Phoenix, Arizona
I have been suspecting a leak somewhere on the property because the water bill has gone up.

I want to make sure I understand your question. I should put the MPV on Filter and run the pool and see if water is coming out of the waste pipe, yes?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
47,255
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
Yes. Is your waste line open to the yard (you can see the outlet) or does it go to sewer?

The only way your CH will fall in your situation is you have a leak. CYA can fall slowly, but if you have been using tichlor, then that is two things pointing to a leak.
 

Copernicu

Bronze Supporter
Jul 22, 2020
32
Phoenix, Arizona
Thank you.

Waste is open to yard. Pool is on in filter setting and there is no leak. I was actually hoping there would be a leak as that would have apparently explained all the issues--increased water bill and chemical issues.

What do I do now? I still suspect a leak on the property. Could it be a pool leak I'm not seeing?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
47,255
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The chemical changes you are seeing implicate a leak.
 

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Copernicu

Bronze Supporter
Jul 22, 2020
32
Phoenix, Arizona
I performed the bucket test with the pool filter off and the auto-fill valve off. After about 22 hours, the level in the pool fell noticeably more than the level in the bucket (not that much). [I'm in Phoenix, AZ, and our highs are currently about 105-110.]

I think this means I have a problem with the shell and not the plumbing? I have a fiberglass pool, which I understand normally can't be drained. The leak detection article has some more info but it's not clear to me what I should do next.

Any advice would be greatly appreciated.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
47,255
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
It can be in your plumbing.
In our climate you can drain a Fiberglass pool. We do not have ground water.

The most likely places for leaks in a fiberglass pool are the places the returns, main drain, etc are punched through. Other would be the skimmer. It is fairly rare to have a leak in the plumbing here as normally we do not have ground movement, etc.

Using dye in a syringe around the skimmer area, the returns, etc would be a logical next step.
 

Copernicu

Bronze Supporter
Jul 22, 2020
32
Phoenix, Arizona
Thank you.

I am thinking I probably need to call someone at this point, as I suspect I'll need help with the fix. I have an independent pool guy who has fixed some leaks for me in the past (had some air bubbles--it was pool equipment stuff, i.e. replaced MPV, that king of thing). Would that be the right person to call for this?
 
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