The Aquascape UltraKlean BioBalls provide pond owners with efficient mechanical and biological filtration, optimizing water conditions. UltraKlean BioBalls are intended for use with UltraKlean Pond Filters. The significant surface area of each ball ensures effective colonization of bacteria, maximizing biological filtration in the filter. Mechanical filtration is provided as the UltraKlean BioBalls create small channels by packing together, leaving behind unwanted debris. During backwashing, the BioBalls are easily stirred up to release debris for removal. 250 BioBalls are included in each box.