Just some info on Nitrate...even without a sandbed, my NO3 levels are undetectable. The rock alone does a good enough job, so NO3 rduction isn't a good reason for sand either.
Really the only good reason to add sand is because you like the way it looks. A nice white sand bed does look nice, but I just did a water change, and the sludge I was able to suck off the BB for only a week gave me 2 5g pails of very dirty water. I'd hate to have that building up in my sand bed.
IF you do go for a sandbed, I'd use a gravle vac to keep it clean.
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Brad
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