dKH testing

[kurtl000]

When is the best time of day to test alkalinity levels cuz i know they change throughout the day. Is there a best time?

[Fant]

Any time should be fine. the alkinity should not really fluctuate as in rise/fall like say pH does in terms of photoperiod. If your not adding a balanced ca/alk system then once the alkalinity is consumed either by corals into calcification or by acids, its not really going to go back up again.