@lowerylisa1 The above does not efficiently work and is a waste of money. It is still better than nothing and it does help a bit.
Reason is, in a cartridge, you are flowing from outside through the cartridge wall thickness to inside and out. i.e. your contact time is maybe at best 0.5 seconds. With ideal and proper carbon filtration set up, you need to flow through a mass of carbon bed say 0.5m to 1m thick and this needs to happen as slowly as possible. This gives you huge contact time with way better results.