Daily water test in evening or morning?

AndyTN

Bronze Supporter
Mar 27, 2019
149
Memphis
I just tested my water when I got home from work which I do almost everyday. I was wondering if it is better to test in the morning before the sun has hit or in the evening so you know how much bleach to add. Testing in the morning could give you more consistent numbers for the past 12 hours with no effect from the Sun but testing in the evening gives you a better idea of how much bleach you need to add to get your numbers right. I may be overthinking it as my numbers are in a pretty good rhythm but I was just curious.
 

Oly

Gold Supporter
Jun 28, 2017
1,169
Fresno, CA
The time of your test will tell you different things. Testing a couple hours after an application will confirm your application effect and your estimations like pool volume.
Testing again in the early morning after a sundown chlorine application and confirmation test will provide you an Overnight Chlorine Loss value which details FC loss not associated with solar radiation and isolates organics.
Waiting 20+ hours after an application will give you an idea of your daily FC loss. This number will change with the seasons. :testkit:
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,526
Northern NJ
There should be little to no FC loss between sundown and daylight on your pool. So the evening FC reading or early morning FC should be about the same.

As Splash said, do it the same time if you can.
 

wogster

In The Industry
Apr 30, 2018
79
Toronto, Ontario, Canada
I think evening is better, if your adding chlorine it has the night to work, before the sun hits it and burns it off.... About once I week, I would say, test both, evening and morning, to see if there is any loss over night, that could indicate problems.
 

AndyTN

Bronze Supporter
Mar 27, 2019
149
Memphis
Are you leaving pool running at night when you add in eve or just adding letting it mix, then turning off?
I will normally test and add chemicals around 6 when I get home from work and turn it off around 8-8:30 before going to bed. This time of year, I am usually leaving it on 24/7 so the fountain can run to cool down the water but that is only for 2 months out of the year.