This quiet power filter is the first with 5 stage filtration: two mechanical, one chemical, and two biological. Fluval C Series provides advanced filtration for cleaner, healthier water with a patented re filtration system. It allows the filter to reduce the water output at the same time increasing the filtration dwell time in the filter. There is easy access to the cartridges for quick and simple cleaning and an indicator that rises when it is time to rinse and clean the poly/foam pad. Includes an extendable intake strainer to help avoid clogging