I got concerned when my subsrate started clumping. Did some reading and found that the smaller (sugar size) sand was better. Not as sharp. and easier for critters to thrive. I have no critters ( worms ect.) in my tank. The DSB helps the critters reproduce which in turns feeds the corals. It also helps with denitrication. I know there has been alot of disscusion about the DBS crashing, but the one of the articles I found on the net claimed that this is unlikely.
http://www.rshimek.com/reef/sediment.htm
And after 9 months of struggling with the tank( algae, corals up and dying and problems with calcium( due to IO salt)) I figure this is the last thing for me to try. Any other suggestions would be appreciated.