IME detritus can accumulate betweeen grains of sugarfine sand in a DSB- even with proper DSB husbandry. Think about it- where do sandbed worms go poop?
		
		
	 
True but other things come along and eat that poop and eventually it gets broken down to nothing or gets worked out of the sand. Is there going to be some left in the sand? of coarse. There is also going to be some in your rocks, in the corners of your tank and sump. If someone wnats to replace some of their sand fine, what can it hurt. I just never did and if you looked at my sand bed 6 months after I set it up or 6 years you could not tell the difference. oh and another key is do not cure your rock with your sand bed.
	
	
		
		
			It's not just DSB's that can bind up unwanted substances- liverock can as well, (thus the birth of "liverock cooking" techniques).
		
		
	 
Yes live sand can and live rock.
There will always be some nutrients in our system and there is nothing we can do about it. Also some nutrients are needed if we got them to zero our corals would die. Zooxanthelle require phosphate and nitrogen to survive.
Fact is it all comes down to good husbandry and for anyone to say there system is the only way is wrong. There are lots of successful ways to keep a reef.
Seems like sometime we like to over do things in this hobby. Lets see how much lighting we can throw over our tank, lets get the biggest best skimmer when it is not needed. Such a waste of money. We throw corals in our tanks that would never be found next ot each other in the wild and we wonder why it died and start pointing fingers at everything. We throw corals together from different reef zones, different flows and different lighting and differents amounts of nutrients.
The tread starter asked a question that really can not be answered because nobody knows, everyones tank is different, some people feed more, some people have better skimmers, some people take better care of their tanks, all the different setups etc.
My first reef tank had a coral gravel bottom with 4 normal output fluorescent lamps  3 grow lamps from the garden center and a philips tl03 actinc lamp it and no skimmer.  Tank did awsum. I would never recommend to someone that this is the way to keep a system. We have progressed over the years and found better ways.
Wow some how I turned this into a history lesson.. I have always wanted to write an article on the history of the hobby.
By the way my post was not aimed at you. It was just at this hole dsb/bb debate in gerneral.
By the way Gary your tank is still one of my favorites. Your tank looks so natural and never looks overcrouded and like everything was just thrown in there. ? I would really like to see some updated pictures of it.
Gary You going to imac? We need to sit down and have a beer sometime, us old timers. You use to use the compuserve fishnet forums in the day too right? My mind is failing me lol.
Dave