Maxspect's Nano-Tech Bio-Block are created using stabilized microbial sewage treatment technology with Biological Aerated Filter (W-BAF). This proprietary technology is formed into inert ceramic blocks which can be placed directly into your sump or filter compartment for aquarium filtration. Each block has an ultra-high surface area of 11,635 square feet, providing ample room for colonization by beneficial bacteria strains that can work to lower nitrites, nitrates, and ammonia naturally.