CaribSea Arag-Alive! Bahamas Oolite calcareous substrate is an oolitic sand with grain sizes of 0.1–1.0 mm. It is suitable for shallower substrate beds and allows denitrification at a depth of 3 cm. Its fine grain size makes it easy for bottom-dwelling fish to move through, and the substrate is also suitable for growing marine plants such as Thallasia...