3C Carbon Cartridge Aquastyle 620/620T

The Aqua one 3c carbon and polymer wool cartridge The 3c cartridge itself is however quite a clever little thing designed with complex aims and objectives in mind. The carbon tray does indeed hold the carbon granules which are an essential and very purifying but can also be messy if left to roll around. The Aqua One 3c carbon and wool cartridges are not designed to grow the beneficial, nitrifying bacteria so often sought after by the fish keeper. 3c cartridges don't always last the full six weeks in between changes and it's worth checking on their performance once per week.