Just about had it now!!!

[trilinearmipmap]

I had some nitrate problems due to overfeeding, the nitrates were about 5 to 10 range, this was earlier this year.

I started adding sugar, went to barely detectable nitrates on the Salifert test, accompanied by much improved skimmate production.

My understanding of how sugar works is bacteria feed on the sugar, the bacterial population locks up nitrates and phosphates, then the bacteria get skimmed out by the skimmer.

I started adding 1/8 or 1/4 tsp of sugar daily in a 120 gallon (I forget which) and gradually increased it to 3/4 tsp daily. Lately I have slacked off and just add 1 tsp every few days when I remember.

Adding sugar is easy and worth trying. I saw no bad effects on my corals though I suggest starting slow and gradually adjusting the sugar dose.

[Reefer Rob]

I'm going to out on a limb here and say I think it's your sand. In my 180G that's been running since January I've gone to 1" of sand for aesthetics that I gravel vac once a month or so. Looking back, the only thing sand has ever done in my tanks is increase nitrates. The more sand I had, the more nitrates I had.

In my last tank I run an remote DSB and had 20 ppm nitrates. After I took it off-line they went to 10 ppm within a week.

With 2"s of sand you would be safe to suck out 1" and gravel vac the rest. Guaranteed you're going to get a ton of crud out of there