I think the key to cleaning an CFC is to rinse it immediately after use. Don't give anything time to settle or dry at all. I blast mine with a garden hose right after fermenters are full. I also have one of those small brushes on a long wire, I think it is meant for keg dip tubes, to shove in from both ends. Soak it in PBW with very hot water and blow through hot water to rinse and it is amazing what gunk you did not know was hiding in it.
I also let in some boiling wort before turning on the water as a last precaution. I have been using it for about 20 years. So far so good.