what time should you test

If you have a party at 5pm-7pm, then check chlorine values and add bleach immediately after people leave, then re-check about 2 hours later, should you have the same values in the morning? Or are the values going to be lower because it takes time for the water circulate to kill all the 'organic matter' throughout the pool?

I added bleach after a party at 7:30pm. I tested water at 9:30pm (FC=17.5, CC=0.5). Checked water at 1:00pm the next day (FC=13).
Nobody was in the pool after the party until 1:30pm the next day. It was cloudy until about 11am, then the sun came out.

The pool passed the over-night loss test the day before.

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
SouthWest Alabama
I test in the evening after the pump has been on for a while. I do it because it's easier for me and it gives me the lowest setting of the day. That way I make sure the FC stays above min.


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
After a large pool party there is extra organic debris in the pool from all of the swimmers that takes at least several hours to all oxidize. Also, you would have lost FC during the morning, even if it was cloudy.
The FC was so high because I had been fighting algae last weekend after my FC dropped to 3.5, plus we had some rain. So I had shocked the pool. Immediately after the party, the FC was 7.5 (it was 16 at 5:30am)

We have a large number of swimmers almost everyday, plus my sister's dog likes the pool, so I can lose about 6-8+ ppm / day.