Just opened pool, Ph > 10 and CC = 5.5

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ColoradoPool2022

Active member
Dec 7, 2022
30
Denver, CO
Pool Size
10880
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-20
Hello again,
We just opened our pool in CO for the 4th season and the chemicals seem to be at their worst. The company that opened our pool on Monday said the Ph was really high (not sure if/how they tested it) and put 64 oz of 20' muriatic acid in. They also put in 2 lbs of 54% cal-hypo shock. I was busy and didn't run my own tests that day (two days ago). I ran my test today and holy cow, things are a mess. I'm mostly concerned with the CC level as I tested twice and got 5.5 and 6.0. That would suggest that my break-even chlorination level is 55! That's >9 lbs of shock and that just feels like a bad idea.

My main question is- do I just drain the pool and start over? Below are my full readings as of today. For now, I'm trying to bring down the Ph and then will work on the CC based on the advice I get here. Thx for any advice!

FC- 0.5
CC- 5.5-6.0
Ph- it was purple. It took 7 drops of R015 to get to about 7.4. That suggests 70 oz of acid but I put in 50 to start and will recheck tomorrow morning. I also turned the pump up to 2,300 RPM.
TA- 130 (for some reason my TA always goes up over short periods of time. It was 80 when I closed the pool in October. Hopefully addressing the Ph situation will get me back down around 100 and I'll go from there)
CH- 370
CYA- zero. I plan to address this after the Ph and chlorine concerns. This was 60 when I closed the pool.
Salt- 3,000. I plan to address this after the Ph and chlorine concerns. This was 3,200 when I closed the pool.
Temp- 68
CSI- pool math can't calculate it given the Ph level
 
If the water is not a swamp, no need to dump.
When doing pH adjustments, do it in .4 reductions. Larger reduction calculations are not accurate. Lower .4, pump running, test 30 minutes later. Repeat until your pH is in the 7s.
Can you go test pH again now?
 
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I don't believe the CCs. It takes FC to make CCs and they burn off rather quickly.

Have you been adding FC ?

Is the cell working yet or is it still too cold ?

Are you sure the chemicals above are all the pool guys added to the pool ?
 
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ColoradoPool2022 said:
The company that opened our pool on Monday said the Ph was really high (not sure if/how they tested it) and put 64 oz of 20' muriatic acid in. They also put in 2 lbs of 54% cal-hypo shock.
Click to expand...
2 lbs of 53% Cal Hypo corresponds to 13 FC in a 10k pool, if I’m running pool math correctly.

ColoradoPool2022 said:
FC- 0.5
CC- 5.5-6.0
Click to expand...
After ~ 2 days.

Newdude said:
I don't believe the CCs. It takes FC to make CCs and they burn off rather quickly.
Click to expand...
@Newdude can you please walk me through that statement? What kind of ratio would you expect to see between the FC added and having been converted to CC, and how quick should the resulting CCs burn off? Honestly looking to learn something from this. Where I live we don’t have winter, so I don’t expect to ever close a pool...
 
ol_whistle_britches said:
What kind of ratio would you expect to see between the FC added and having been converted to CC,
Click to expand...
An equilibrium between input (FC) and output (CC) as its converted. If the sun is out, you aren't going to stack CCs to get to 6, they will burn off as they accrue. Maybe it'll get to 2 CCs but not 5. If the CCs are burning through the FC that quicky, you'll have no more FC to contribute to the equation and the sun burns off the CCs a short time later (15 mins ?) and you have 0s / low for both.

Some chemicals such as MPS (non chlorine shock) or Sulfamic Acid will show as CCs.

Ammonia is another possibility but you'd have to add 10 FC and test pretty quickly to see you lost 9 of it and have 6 CCs because they haven't burned off yet.

Or its dark out and the CCs did stack.

Or testing error.

We're still working out the details. :ROFLMAO:

Deep dive:

CC - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
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@Newdude thanks for the response. I guess I didn’t realize the CCs could burn off that quickly. Sounds like your saying sunlight can breakdown CCs at a much higher rate than FCs, so it really shouldn’t be measurable in the timeframe mentioned. I didn’t realize you could burn >5ppm CC in a day.

PoolStored said:
I thought the same thing, but low pH is typical with Ammonia...why the high pH?
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I read that in the wiki and picked up on the same thought. I though the wiki may have a misprint. I thought ammonia was a somewhat basic chemical, which would lead toward a high pH, no?
 
ol_whistle_britches said:
I thought ammonia was a somewhat basic chemical, which would lead toward a high pH, no?
Click to expand...
Oxidizing ammonia creates acid by releasing hydrogen.
More than 95% of ammonia is in the form of the ammonium ion (NH4+)
2NH4+ + 3OCl- --> N2 + 3H2O + 2H+ +3Cl-
The creation of the H+ makes the pH drop.
 

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PoolStored said:
Oxidizing ammonia creates acid by releasing hydrogen.
More than 95% of ammonia is in the form of the ammonium ion (NH4+)
2NH4+ + 3OCl- --> N2 + 3H2O + 2H+ +3Cl-
The creation of the H+ makes the pH drop.
Click to expand...
But it doesn’t oxidize until you add the FC, right? So wouldn’t a symptom of a pool suffering an ammonia problem that has built up over time be indicated by a high pH (until you start adding FC)? I.E. if you closed the pool for months and walked away from it?

I haven’t done chemistry since college. I totally believe you.
 
ol_whistle_britches said:
But it doesn’t oxidize until you add the FC, right?
Click to expand...
HOCl and OCL- are about 50/50 at pH of 7.5.
As pH rises, HOCl decreases and OCL- increases (and the converse)
There was likely FC in the pool when they closed.
As the oxidation occurred, the OCL- (the part of the FC consumed in the oxidation of ammonia) decreases, the H+ (hydrogen ion) increases which decreases pH, the HOCl in equilibrium with OCL- is converted, and the cycle continues, which result in an increase in H+, which is a lower pH.
 
Wow, thanks for all the eyes on this! So after adding the 50 oz of acid yesterday the Ph was down to 7.8 this morning so I added 10 oz more acid going for 7.4. The FC still showed 0.5 and the CC 5.5.

I should also add that we have a security cover which was closed since opening the pool on Monday (yes, even after they added a bunch of acid and shock; not ideal but with the weather it had to be closed or it would be covered with all the debris that falls from the neighbor's willow tree). I did leave it open for about 2 hours yesterday after adding the acid, but closed it up again for the night. I'm going to leave it open most of today to see if we can burn off some of that CC.

It would seem I have an ammonia issue- with the exception of the high Ph (??). I guess I should go with the assumption that it's ammonia and treat it as such? I do happen to have a fish store near the house and could get an ammonia test but not sure if I should rely on that based on the article mknauss shared (Ammonia - Further Reading).

If we agree I should pursue this as an ammonia problem then here is my next obstacle- I have searched high and low in Denver for three years for liquid chlorine to no avail. The pool stores here don't stock it (other than drums of commercial grade stuff) and the only time I did find it was late in a season at Walmart and I'm pretty sure it was expired as it didn't move the FC levels anywhere near what it should have (I recall checking the label after the fact and it was maybe a year old). So my only option is granular shock (yes, won't be cheap). Any concerns with going that route? I figured I'd just have to give it a bit longer to circulate- maybe 60 minutes instead of the 30 recommended in the article? I should say that I noticed last week that my Walmart had liquid chlorine again but I really don't think I should trust it- and if powder will work I'll just go that route and avoid the guessing and hassle.

We'll have good weather in Denver tomorrow so hoping to tackle it then...
Thank you!
 
If it is ammonia, then the pH and TA will drop as liquid chlorine is added.

Why Does pH Drop When Treating Ammonia With Liquid Chlorine?​

Oxidizing ammonia creates acid by releasing hydrogen.

More than 95% of ammonia is in the form of the ammonium ion (NH4+)

2NH4+ + 3OCl- --> N2 + 3H2O + 2H+ +3Cl-

When adding 12.5% sodium hypochlorite (liquid chlorine) to a pool to oxidize ammonia, every gallon of liquid chlorine will create the equivalent of 15 ounces of 31.45% hydrochloric acid.

10 gallons of 12.5% liquid chlorine added to 25,000 gallons of pool water with ammonia will lower the TA by about 23 ppm or the equivalent of adding 150 ounces of full-strength 31.45% muriatic acid.

Every 8.53 gallons of 12.5% liquid chlorine equals about 1 gallon of 31.45% acid.
 
Bperry said:
Walmart, Home Depot, Lowe’s, pool stores, hardware stores, all of those guys should carry liquid chlorine. They just probably call it Pool shock.
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Maybe they should, but in Denver they don't. None of the pool stores that I've called and only Walmart of the big box stores have it (see comment above re: Walmart chlorine; I should also mention that Walmart keeps it outside with wild temp fluctuations here in Denver).
 
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