Optimized filtration substrate with perfect volume utilization, long service life and very high degradation capacity. SUBSTRATpro consists of sintered quartz in bead form. The spherical shape ensures high density. This makes it possible to use the entire filter volume (baskets or filtration modules). In addition, the optimized surface of the small beads ensures intensive colonization by the important cleaning bacteria. The result is a thick bacterial mat. The high bacterial count helps reduce nitrate load peaks and extends the life of the filter material. EHEIM SUBSTRATpro is suitable for fresh and salt water, is washable and can be used several times.