How does CH jump over the winter?

[salty87]

How does CH jump over the winter?
Where's the calcium coming from?
Does lower TA play any part in this?

Last year CH was consistently in the 425 range. Running the test (twice) it's now 600. And this is after replacing some water last year. Rough estimate is 25% of 25k gallons. Pool Math wants 50% of it replaced now.

These are the full test results:
FC 4.5
CC 0.5
TC 5.0
CH 600
TA 50 (was 110 last year)
CYA 40 (was 60-70 before replacing water last year)
pH 8.1
-On my way outside to add some acid. Will raise the TA, too, but need to buy baking soda. Haven't had to add any before.

PB filled the pool in 2016 with trucked-in water of unknown quality. I found TFP right after they 'handed over the keys' leaving me clueless. Water was replaced with rain water of fantastic quality mid 2017. Some work needed to be done on our rainwater tank requiring the water level to be dropped a couple feet. It was a great chance to lower CYA and CH. CYA dropped from 70 to 40 but the CH level didn't really budge. CH test on our rainwater shows no calcium. The solution doesn't turn red.

Thanks

* 2018 reagents being used.

 

[Texas Splash]

While your plaster should be fully cured by now, you might still benefit from some of the info in this thread: New Pool Plaster does not always cause CH rise. But this seems odd:

CYA dropped from 70 to 40 but the CH level didn't really budge.

You would think the CH would drop to some degree right? Over this past winter, did you add fresh water much? If so, was it from the rainwater tank or local water supply?

Also, do you use a speedstir?

I suspect you are in the process of doing a post-winter adjustment to all levels as our weather is picking up. If we don't receive any input from one of our plaster guru's, I can certainly "ping" one later if you like for some additional perspective. Keep us updated to any concerns, and have a nice weekend.

 

[salty87]

While your plaster should be fully cured by now, you might still benefit from some of the info in this thread: New Pool Plaster does not always cause CH rise. But this seems odd: You would think the CH would drop to some degree right? Over this past winter, did you add fresh water much? If so, was it from the rainwater tank or local water supply?

Also, do you use a speedstir?

I suspect you are in the process of doing a post-winter adjustment to all levels as our weather is picking up. If we don't receive any input from one of our plaster guru's, I can certainly "ping" one later if you like for some additional perspective. Keep us updated to any concerns, and have a nice weekend.

Thanks for the link. I haven't read that one before.

I was surprised when the CH didn't drop after replacing water...disappointed.

Speedstir- affirmative

We only have rainwater. Refills over the winter were normal. Now that you ask there's a dedicated rainwater tank for the pool, 1k gal. I've tested the house water but haven't tested water from that dedicated tank. It probably doesn't have a liner like the house's main tank. The pool's tank is aluminum. Could it be leaching calcium into the pool? I need to test its water.

You have a great weekend too!

 

[cfherrman]

One user here was getting ch 40 off his roof from rain water, stange things.

 

[salty87]

^ good to know. The pool's tank is empty as a pipe burst this winter. Need to fix that and collect some water before it can be tested.

In the meantime Pool Math tells me to keep the pH down and a lower TA is better with high CH. Higher TA and high pH push CSI near .6 and the trouble zone.

 

[ping]

What are you using for chlorine?

 

[salty87]

What are you using for chlorine?

Liquid bleach. Same source/brand as before.