How did my pool chemistry correct itself?

[Pool-in-the-Hills]

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]

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]

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]

Read here about dry acid - Acid - Further Reading

Lowering pH lowers TA.

CYA testing errors can be +/- 20 ppm.

CYA Testing - Further Reading

www.troublefreepool.com

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

And keep pH in the 7's.

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