yes, aragonite sand is the very best, though you must have lots of live stuff- critters, worms, snails, etc... otherwise it will calcify and become like a brick. a plennum under 3-4 inches of aragonite will act as a perfect denitrification bed and solve your nitrate problems, it will also cut your water changes down to ever 3-6 months depending on how good your skimmer is and how much you feed your fish. i only had a few fish in my reef and they ate out of and off of the reef(5 fish in a 120 show). i added no fish food for them and did water changes once a year just cause. never really had any nitrates 0-5ppm tops. happy reefing