Steve,
Marcs article looks pretty decent. Randy has a good in depth one with a lot of options.
Nitrate in the reef aquarium
I've tried almost every method mentioned in each article, and I feel the remote deep sand bed is hard to beat for simplicity, and cost if you have the space. Here is a cool older RC thread from back when Anthony Calfo had his own expert forum here.
Remote DSB with Anthony Calfo
If you want to try a sulfur denitrator I have a 4" PVC one a club member made for me. I would let it go cheap. It was built based on this thread.
DIY sulfur denitrator
In the mean time I would try to siphon any detritus with your water changes. If I remember right you have a hang on overflow. If you are running the sponge in the back to silence it you need to keep it clean.
I know a few months after you got the tank running you added a fuge. Is it over crowded to the point macro growth has slowed? Don't be afraid to thin it out. I often see people proud of a packed fuge, but in reality the macro on the bottom is usually rotting. Rotting macro will just add to the problem you are trying to fix.
Have you tested your RO/DI?
Are you maybe overfeeding? All proteins contain N. When metabolized most of that N comes out the other end as NO3.
Don't be afraid to run your skimmer wet. Dry skimming just leaves sludge in the neck that will add to the problem.
Hope my rambling helped some,
Josh
By the way please read up a lot before jumping into something like carbon (ethanol/vinegar/sugar) dosing. I'm not saying it doesn't work, but can go bad quickly. I know of one local that lost his tank due to overdosing.
I've seen a lot of healthy looking tanks with 100ppm NO3. I wouldn't panic, but getting it under control will improve growth/health of your coral. Typical ocean level is 0.1 so you are only 1000x high...
