SubstratPro consists of spherical sintered quartz. The spherical shape allows for a high bulk density, enabling full utilization of the volume in the filter (filter baskets or modules). Additionally, the optimized surface of the beads promotes an intense colonization of essential cleaning bacteria, resulting in a dense bacterial mat. The high number of bacteria also helps to better reduce nitrite spikes and extends the lifespan of the filter material. Eheim SubstratPro is suitable for both freshwater and saltwater, is washable, and can be reused multiple times.