BIOHOME Ultimate is a smaller size pellet which is ideal for small internal filters. Also ideal in overhead filters, external canister filters of all sizes, and sumps. It is exactly the same pellet and size as BIOHOMEMini Ultra except for added trace elements which are included in the pellet itself giving it the ‘red/brown’ appearance.These elements added to BIOHOME Ultimate are: Silica, Titania, Alumina, Ferric Oxide, Lime, Magnesia, Potash, Soda, Phosphorus Pentoxide, Chromium Sesquioxide, Manganic Oxide, Zirconia, Hafnia, Zinc Oxide, Barium Oxide, Strontia, Stannic Oxide, Sulphur Trioxide. (from XRF analysis).Beneficial bacteria colonizes very quickly in BIOHOME Ultimate due to its high porosity. It also recovers very quickly from the use of medications and can easily be transferred from one system to another.BIOHOME is a highly effective biological filter media. Good mechanical filtration (ie sponges, poly fibre, filter socks etc) must be provided prior to water passing through the BIOHOME bio filter media to eliminate clogging of the system.