How did my pool chemistry correct itself?

Apr 6, 2021
20
Litchfield County, Connecticut
Pool Size
15000
Surface
Plaster
Chlorine
Liquid Chlorine
I'm a newbie (obviously) and am just curious about how my out-of-bounds pool chemistry corrected "itself." Here is where it was on 7/29:
FC=2.5
pH=7.8+
CC=0
CH=175 (goal is 250-350)
TA=140 (goal is 70-90)
CYA=20 (goal is 30-50)

I added pH Down to start reducing pH. It would work, but only for a day, so I would add more pH Down, along with LC 10% to raise the chlorine (after it would drop to almost nothing). This has gone on for two weeks. Levels yesterday were:
FC=1
pH=7.2
CH=175 (still needs to be raised to 270 - I added Calc. Chlor.)
TA=100 (almost there - this is due to the pH lowering, right?)
CYA=30 (ideal - how did this happen??)

I'm curious so that in the future I will be able to figure out how all of these levels affect each other. Thanks!
 

mickey4paws

Bronze Supporter
LifeTime Supporter
Apr 10, 2009
743
S.E. MI
Hi there, lowering your PH helped I'm sure. I've never used PH Down so I'm not sure what that is. I use muriatic acid to lower PH. But I would recommend getting your FC up right away. With a FC of 1, algae will develop sooner rather than later, if not already. It wouldn't hurt to do an overnight chlorine loss test. With a CYA of 30, your target is between 4-6ppm.
 

Bperry

Gold Supporter
Aug 20, 2020
1,071
Knoxville, TN
Pool Size
27000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
CircuPool RJ-60
pH down adds sulphates which can cause a problem over time. Use muriatic acid instead.

actually your original levels are better than the new level. Get your chlorine level up quick. The TA will come down on its own over time as you manage the pH in the 7’s.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
29,782
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Read here about dry acid - Acid - Further Reading

Lowering pH lowers TA.

CYA testing errors can be +/- 20 ppm.


Maintaining your FC above minimum should be your primary mission - FC/CYA Chart

And keep pH in the 7's.

The other chemicals are secondary to FC and pH. Don't get distracted by big numbers.
 
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