What factors lower nitrates when not performing water changes?

[ripcord]

I use a sulphur denitrator, works wonders!

 

[Charles Zinn]

No it's established now, but lately nitrates are dropping..haven't done a water change in 6 months..tank looks great tho

I have heard that as corals grow into colonies they use up the nitrates and phosphates.

 

[Randy Holmes-Farley Verified Community Expert]

I put my skimmer on a timer it goes off during the night time cycle , turns on when my lights start ramping up , it’s helped keep the nitrates up

I personally wouldn't want to do that since you lose oxygenation when it is most useful: at night.