Dry aragonite is a good option. Crushed coral is pretty popular but after some time, detrius and uneaten food can get trapped in there and cause nitrate issues. Not as big of a deal if youre planning on keeping the tank a FOWLR
tank, but if you ever get the itch to put corals in there, and you probably will, you wont want any nitrates, so cc isnt a good choice there.
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