About this item Honeycomb activated carbon have effectively increase contact area. Efficient filtration to easily create your own filter cylinder. Effectively help you solve the problem of water color yellowing or greening odor residue brown algae chlorella and so on High iodine value better adsorption strong adsorption can be used repeatedly. Iodine value greater than 800. The strong adsorption and decomposition force can firmly control and oxidize the adsorbed material which improves the adsorption efficiency and extends the service life Rinse with water before use then put it in the fish tank for use. Easy to clean and more healthier. NOTE: please make sure that orient the filter hole towards the direction of the water flow when placing the water purifier cube. We recommended to change every 3-6 months for better using Positive cubic design easy to place neatly with processing and compression. Two size filters for optional big one is about 10 x 10 x 10cm (3.9 x 3.9 x 3.9inch) the small one is about 10 x 5 x 10cm (3.9 x 1.9 x 3.9inch) NOTE: May be the item will be detachment on the edge during delivery which is a normal phenomenon but does not affect the function please think it over before purchasing