BIOSTEPS WITH 18-WATT UV MATALA: BIOSTEPS WITH 18-WATT UV $368.50 SKU: MAT33 QTY: Click here to save 5% off of your order! BIOSTEPS WITH 18 WATT UV An ideal filter for ponds up to 2600 gallons; Koi ponds up to 1330 gallons. Steps-wise transition from mechanical filtration to high efficiency biological filtration. Secion 1 is the Sedimentation Chamber - water inlet and large partical sedimentation. Sections 2-3-4 contain Matala media in varying densities. Section 5 is Fuji Stone for nitrification, denitrification, and buffering of pH and water mineral contents. Section 6 is polishing chamber for water conditioning and polishing. Recommended flow of 800 gph. 18 Watt UV can prevent blooms of unicellular algae, bacteria, and parasites.