Never ever skip you water change!
 

Ok so I used to do WC of 2/3 gallon every two weeks and then moved to weekly 2/3 gallon and then put up a protein skimmer and moved back to 2/3 gallon every two weeks. Oh well, I don't have nutrient issue since I got the skimmer along with a refugium. Previously, when I was in biweekly WC routien, my calc/dkh wouldn't change much (stayed around 440ppm and 8-10dkh). Corals were, well....growing but not growing fast since I didn't have a good light on them.

So few weeks back, I got much better light and corals (particularly birdnests) started growing crazy. I kept up with my biweekly wc. Today I thought about checking my params and guess WHAT! The corals sucked up my calcium to 380ppm and dkh fell to 6 :O I did a 5 gallon WC 2 days ago but didn't put much of the supplements I guess. 10 gallon of saltwater is being prepared as I write this.

So the moral of the story; water change doesn't always mean that you are doing it for nutrients (my reliable LFS once told me this); its also to replenish the supplements!

No damage done though. Calcium didn't take a big hit (many reefers do keep at 380ppm) but the dKH did take a BIG hit. I wonder why non of the corals reacted to this..........