I know that CO2 is used during lighted hours, and not used during the
dark. Thus, if one is trying to conserve CO2, or avoid stressing the
fish, CO2 injection is often stopped at night.

Is there some sort of similar rule to follow regarding nitrates? Do
the plants absorb them during the day, during the night, or
constantly? Is there any real benefit to dosing in the morning, or
evening?
--
"Oh no! look over there! How did a Chupacabra get into the house? Quick!
Hide all the goats!" - Lisa, Girl's Bravo, English Dub
Abraham Evangelista