bavass
Aquarium Advice Addict
You've mentioned several times about using "BioClean". Not sure what that is, but if it's some type of bacterial supplement, and there's nothing in there for the bacteria to eat (ammonia from fish), then the bacteria is going to die off. And bacteria dieing off creates... nitrates.
I did some searching and found several snake oil... err... I mean "aquarium helpers" called "BioClean". Not sure what exactly the stuff is, but I'd wonder if that's not the source of your mystery nitrates - either directly or indirectly.
Adding uncured reef rock will cause die off, but I wouldn't think that'd be enough to boost the nitrate levels that much in a few days. I'd be suspicious of the stuff you're putting in the tank.
you might be onto something here with the bacteria dying because of no fish and no ammonia. I did a 15g water change yesterday and added a vial of the Biodigest and a vial of Bioptum well this morning the Nitrates are lower they are below 5ppm. Adding the two Green Chromis might have been the ticket. The bacteria might have died because there were no fish in the tank. It is lower the morning than it was after I did the PWC yesterday. Keep fingers crosssed! I will try and get a pic of sometime today of the tank and what it looks like now!