Ok. I'm going to get into this conversation now.

My question is, what are you feeding your fish, how much per feeding, and how often?

Overfeeding will cause this problem and you'll never get rid of it if you don't cut back. You cvan feed your fish everyday or even more than that, you just can't feed too much because it will just load your system up with nitrates.

As for the live rock, you can get it on eBay and other places for $2-3/lb including shipping if you are just patient and look for a good deal. I have not bought LR from a store since the first piece or two I got to start the tank. If you don't want to get LR get some dry base rock and give the bacteria a place to grow and spread to. By getting dry rock, your "basically" doing the same as having the Bio-Wheel filters, without the splashing and noise.

Once you get the overflow installed and the macro algae growing, I am willing to bet lots of money that you will no longer see nitrates after it has "broken in", meaning the bacteria colony has moved in.

As for the DSB, it si quite important to have "stirring animals" that live in your sand. They do not disturb the denitrifiying bacteria since they do not bring oxygen with them and leave it. Mainly they stay in the first couple of inches of sand and eat all the detritus and waste that creates the dreaded black pockets of death. Nassa snails tend to do a great job, as well as a few others(I like these cause they had lots of babies and I've got them everywhere now). It is also very important to have a nice variety of worms creeping their way all throughout your aquarium. Having a great biodiversity is the best and most sensible way to keep a great aquarium. I always say, "Let nature do its job and help it if it needs little help."

If I were you, I would try and get a couple of pieces of LR from the bottom of someone else's well established aquarium. The pieces touching the sand will have the great number of creatures that roam the rocks, as well as the sand dwelling stuff. I love watching my spaghetti worms and others cleaning the surface of the sand and keeping it clean of waste.

Time is the only true cure for any problem. Never try and "quick" fixes because they don't get rid of the problem, only mask it.