I have one of the filters used for about a week, until I saw black crumbs in the water. Hoping this is an isolated case, I have the cartridge replaced directly, but had the very next day the same result. I once let after inserting the cartridge filter two complete filling and thrown away the water both times.
Since the filter otherwise perfect fit and gets through the water, I forgive anyway two stars - but have now but the original filter ordered because I feel more comfortable with it.