CaribSea Seaflor Special Sand Marine Reef Substrate Aragonite Aquarium Fish Tank

Caribsea Seaflor Sand – Aragonite Substrate (1.25–1.95mm Grain Size). With a carefully engineered grain size of 1.25–1.95mm, this substrate creates an optimal pore water space, ideal for plenum-style nitrate-reducing beds and deeper sand bed systems.

eBay