We have the same lighting and the same tank at our store, we keep all our clams, from crocea, maxima, aquamosa to derosa on the sand bed. However, they'll be purchased within a month or two so I don't know what's the long term effect on them, but they have never died or change color on us. We have one crocea that's been sitting on the sand for at least 3 months now and it's doing just fine.