water testing

[manners]

i do a 1o % water change every week and i was wondering when the best time to test the water is? before the water change, after, in the morning, at night?? ive been doing it the day after at 6pm ish but i check the ph in the moring right after i turn on the light

 

[sly]

Your pH drops at night when the lights are off. If you check it right when the lights turn on, then you may get a reading that is lower than what it would be during the day.
When I do water tests, I go for the best average. I try to do the test about midway through the day while the lights are still on. When you do a water change, I would wait about 24 hours before testing the water. This gives the salt time to fully equalize in your tank before testing.

 

[gmann1139]

Test before your water change. Its when your tank is at its 'worst', and the water change will dilute any possible issues.
As far as TOD, I usually turn my lights on a couple hours before I test, to try and simulate 'day' conditions.
But if I test with the lights off, I know my pH is going to be low. I've kind of figured out what the correction is.