Too High CH Level 4 Months Post Resurfacing

[Elian]

Had pool resurfaced with a pebble finish on 11/1/2022 and builder did initial startup. I took over maint and chem balancing from the PB on 11/6/2022. Per TFP forum recommendations I followed NPC startup guidance processes. On 11/27/2022 started using a Taylor K2006-C test kit and tested CH to be at 330ppm. Kept it all balanced and chlorinated with liquid chlorine till I converted back to my SWG system on 12/1/2022. Since SWG conversion on 12/1/2022 I have kept the water perfectly balanced and within the Pool Calculator recommended CSI ranges.
Today I decided to randomly test my CH since I had not done this for the past three months. I was shocked to see my CH is now at 550ppm. I verified this by retesting different pool water samples three times. I also verified my city tap water is at 100ppm CH.

I'm totally baffled as to how my pool water could climb from 330 to 550 ppm CH over three months. I have not been adding any chemicals other than diamond brand pool salt from lowes to get my salt level to 3600pppm for the SWG startup, two bottles of Jack's magic magenta during initial startup, four pounds of baking soda during startup to raise my TA and since then lots of muriatic acid to control my constant creeping pH that I attribute to the new refinish and SWG system operation. My current levels today are: FC 5, CC 0, CYA 40, TA 70, pH 7.9, CH 550, CSI 0.22.

Can anyone help me out on why my CH may of gone so high so fast? Also what I may look to do to prevent this from happening again if I drain my water down and do a partial refill to get this CH back down to a level of around 300-ish? Thanks.

 

[Mdragger88]

What is the ch of your fill water?

 

[mknauss]

Calcium only has defined sources. Normally, it is the fill water that is used to make up for evaporation. Yours at a CH of 100 would have meant you need to replace two full pool volumes due to evaporation in that time period, not likely.
Other is chemical additions, you say you have not done that.
Then there is from the plaster itself. Your current levels do not show your water to be aggressive.
Last is testing error. Sounds like that is not true.

So, look at all those above and see what could have added the calcium.

 

[Elian]

What is the ch of your fill water?

100 ppm CH city fill water

 

[Elian]

Calcium only has defined sources. Normally, it is the fill water that is used to make up for evaporation. Yours at a CH of 100 would have meant you need to replace two full pool volumes due to evaporation in that time period, not likely.
Other is chemical additions, you say you have not done that.
Then there is from the plaster itself. Your current levels do not show your water to be aggressive.
Last is testing error. Sounds like that is not true.

So, look at all those above and see what could have added the calcium.

This is what I'm looking for some expert advice on . One of the first things I considered was maybe the resurfacing plaster dust deposited something leading to this high level CH of my pool water. But I did some brief research and did not notice any mention of newly built or resurfaced pools leaching calcium or them commonly releasing something causing CH levels to elevate. Who knows maybe I missed something. Is fast creeping CH to too high levels on a new cement/plaster pool build or a recent resurfacing a thing? Thanks...

 

[YippeeSkippy]

After the refinish you brushed a lot, right?

 

[proavia]

It may be prudent to revisit your testing technic ...

Are you using a speedstir (or similar) for testing or are you manually mixing/twirling?

Outline your CH testing.....

• water sample size
• how many drops of R-0010?
• how many drops of R-0011?
• how many drops of R-0012?
• are you mixing well if manually twirling?
• are you holding the reagent bottles completely vertical?
• are you allowing the drops to fully form on the tip and not fording the drops off?
• are you continuing the test to completion each time? Continuing until the last drop of R-0012 doesn't change the color any further and then subtracting the last drop that didn't change the color?
• have you been consistent with your testing method from your first tests until now?

Are you using the Pool Calculator (no longer updated) or PoolMath?

 

[Elian]

After the refinish you brushed a lot, right?

After the refinish you brushed a lot, right?

Yes. There was silly, crazy amounts of white, cloudy, plaster dust in the water immediately after brushing for I'd say almost two months. Finally I got rid of it all where the pool is super clear now.

 

[Elian]

It may be prudent to revisit your testing technic ...

Are you using a speedstir (or similar) for testing or are you manually mixing/twirling?

Outline your CH testing.....

• water sample size
• how many drops of R-0010?
• how many drops of R-0011?
• how many drops of R-0012?
• are you mixing well if manually twirling?
• are you holding the reagent bottles completely vertical?
• are you allowing the drops to fully form on the tip and not fording the drops off?
• are you continuing the test to completion each time? Continuing until the last drop of R-0012 doesn't change the color any further and then subtracting the last drop that didn't change the color?
• have you been consistent with your testing method from your first tests until now?

Are you using the Pool Calculator (no longer updated) or PoolMath?

Outline your CH testing..... I'm pretty confident I'm testing it alright. Answers below:

• water sample size
  • first I did it with 25mL then the next two I did with 10mL so as to conserve reagent drops for such high readings. I pulled new water samples for the second and third tests.
• how many drops of R-0010?
  • 20 drops w/25mL sample and 10 drops w/10mL sample size
• how many drops of R-0011?
  • 5 drops w/25mL sample and 3 drops w/10mL sample size
• how many drops of R-0012?
  • 25 mL sample demanded 45 dropwise to turn blue and 21 dropwise for the 10mL sample size to turn blue
• are you mixing well if manually twirling?
  • yes
• are you holding the reagent bottles completely vertical?
  • I always do this
• are you allowing the drops to fully form on the tip and not fording the drops off?
  • Yes I allow the drops to fully form and release under their own tension or weight
• are you continuing the test to completion each time? Continuing until the last drop of R-0012 doesn't change the color any further and then subtracting the last drop that didn't change the color?
  • Yes I do all my reagent tests till the color change is permanent
• have you been consistent with your testing method from your first tests until now?
  • I believe so but cannot say for sure for CH as the only other time I tested for my CH levels was three months ago. However my overall reagent testing techniques are consistent.

Are you using the Pool Calculator (no longer updated) or PoolMath? I use the web-based Pool Calculator as it's more convenient for me - I was not aware it's not being updated or supported anymore. I also have the Pool Math app but so far only use it's Effects of Adding feature (very helpful feature by the way!).

 

[proavia]

Great! Sounds like you are doing the test correctly.
Still weird to see that much of a CH rise in 3 months ... 330 to 550.
It could be that the PB had the pH quite low during the first 28 days and when they handed the pool over to you. This could cause most of the surface to dissolve - more plaster dust. Also, they may have added an accelerant to the plaster mix to help it dry faster. Both of these may have added to your increased calcium over the last3 months.

So your last test was 550. Test again in 2 weeks and then again 2 weeks after that. Report back in this thread with your test results.

For now, post a full set of test results from your last testing.
FC
CC
pH
TA
CH
CYA
Salt
Water temperature

Also, test your fill water - pH, TA, CH only and post those here.

Moving forward, it may be best to use PoolMath.
Once you get used to it, it's great.
Be sure 'Track CSI', 'Track Salt' and 'Track Water Temperature' are checked.
And also share your results here (user profile here and in PoolMath must match). This will show the last test results you enter when someone clicks your profile pic and then selects the blue 'PoolMath Logs' icon. Click my profile pic to see what I mean.