Ocean Free Activa Block - Super Charged Activated Carbon (equivalent to 10kg activated carbon) Carbon block 250g gives the same results as a 10kg bag for removing pollutants, odours and medications. OF ACTIVA BLOCK is a super-charged activated carbon block designed to maximise absorption of aquarium water colouration, odours, toxic pollutants(e.g. insecticides and chemicals) and medication. Ideal for all types of aquarium. Highly porous natural Bamboo Activated Carbon and Sepiolite Clay minerals are precision-cut into a Cuboidal Matrix Design featuring 1400 micro-tunnels; this greatly increases its surface area and boosts its ability to draw out toxic pollutants from your aquarium water quickly and efficiently. As a result, this little 250g cube packs the equivalent absorptive capacity of 10kg worth of regular activated charcoal powder, or 40 times its body weight in absorptive power! FEATURES Results equivalent to 10kg (250g) of activated carbon Rapid absorption of toxic pollutants, colouration, odours and medication in your aquarium No pre-rinsing and holding bag required No precipitation and staining unlike activated carbon Freshwater and Marine APPLICATIONS ACTIVA BLOCK can be used in any fish tank/sump tank or any water holding tanks that you wish to remove toxic pollutants/colouration/odours/medication.