All above is very well said.
No3 will accumulate in a long run even with water changes.
Flow is very important.

BB here also.
.

Sand is a real PTA with the 50X flow in my tank. I only have 1/2" to 1" for looks, and I'd ditch it in a heartbeat if I didn't like the look of it so much.

Running my 75 with a full load of SPS, 5 fish, 70# of rock and no sand, I had 0 NO3 every time I measured. No gadgets, no NO3 removal stuff. 10g water change every two weeks, Ca reactor for Ca/alk and nothing else. No Mg, no supplements, etc. My tank did just fine and grew faster than I wanted it to. The BB allowed much greater flow than sand would have allowed, which results in thicker SPS growth. After 6 months the bottom was covered in coraline and such anyway, so it looked ok.
That being said, I miss the times sitting in front of the tank at 3am with a flashlight watching all the cool critters from the sand bed.
My new tank will have some sand for decorative purposes as well as giving me back some of those critters. I do not consider sand neccesary for NO3 removal, but that's just my experience. I would never use a DSB again, as I feel this is just a time bomb waiting to kill the tank. Might be 4 or 5 years down the road, but it will go boom. Again, YMMV

Well with my tank its a 120 gal. with a75 gal sump, ATI BM 250, ozone 20mg, 28 gal with 4" Sand bed not lit.
I have a 5" Foxface
4" kole
4" purple tang
2 clowns
4 Chromis
Royal gramma
Algae blenny
3" Lammerick angel
2 Blue linkia's
Orange brittle star
Leopard Brittle star
2 peppemints shrimp
1 cleaner shrimp
assorted snails

I wonder if that is alot i feed 3 times aday with small feeds

That is a heavy bio-load, and with 3 feedings a day, ya, you might get a nitrate problem.

I had 2 tangs that grazed on tank stuff, a pair of clowns and a chromis. I feed once per day with mysis and added about a 2" x 4" strip of nori for the tangs.
Honestly, some of the nicest tanks I've seen used only a skimmer and reactor, good lighting, minimal feedings and were with or without sand. Sand never appeared to be the deciding factor in a nice tank, rather stability, frequent water changes and minimizing nutrient input.

thanks Brad I didn't think that feeding flakes 3 times per day would have a impact on the nitrate problem. I guess i will shorten the feeding down and figure out a way to maybe get rid of some fish I was thinking of taking out the purple tang. and the foxface may be

Aesthetically speaking I like BB in small tanks, its kind of like a minimalist look in a way. However, I think when I set up another large system I will go with a sandbed for looks more then anything.

Mike, it's a balance really. If you can control the NO3, and keep it in acceptable range, then changing the fish load/feeding might not be required. For me, corals were my primary concern, so I managed my tank to emphasize those. For people that prefer fish over coral coloration, then some NO3 is to be expected, and as long as it's manageable, it's not a large concern. And instead of flake I would switch to pellets, as those tend to end up in the fish more so than flakes (IME). If you feed any frozen foods, rinse well before feeding. If you can keep NO3 below ~20 ppm, I wouldn't worry too much. If you sit around 40+ppm, then maybe rethink what you're doing.

Agreed. While I think the sand will work against what I'm trying to do, my new tank will be more of a display than previous tanks, and for looks, I'm going to go with a 1/2" of sand, at least in the viewable areas.

I totally attribute any success I've had in the hobby to the removal of my sandbed. While I do miss it at times (esp when I'm trying to reach the bottom of the tank with my hands) you can't beat BB for siphoning ease. The amount of detritus that builds up in a single week makes me shudder at what was getting mixed into my sandbed. No wonder I always had issues with my tank with sand.