Crabbie
You should occassionally clean all equipment to keep it functioning as designed.
This includes the insides walls/chambers, all moving parts and all tubing.
Mechanical filter media and chemical/carbon should be cleaned and replaced as necessary.
Biological filtration media should not be cleaned as often, but should be swished around in a bucket of the still warm tankwater, removed when you do a partial water change.
This is just to remove any detritus or particle build up - but protects the bacteria.
Cleaning mechanical filter media, floss or fiber - I like to rinse this stuff under warm tapwater. The chlorine in the water will tend to kill bacteria. This is my aim when dealing with mechanical filters.
Kill bacteria - otherwise this media material will harbor bacteria - and become biological filters. Not my intention at all.
A quick rinse in some RO or dechlorinated tapwater will rinse off any residual chlorine - and back the filter media goes into my system.
No matter what you do - it's usually best to only clean ONE filter at a time. Then clean the other(s) on separate schedule. This will help reduce the chance of disrupting the balance of your tank.
Staggering the cleaning - by cleaning one piece of equipment one week, then cleaning another piece the next week - will help from tossing your system out of whack.
Even though mechanical filters are used for removal of particulate matter - if they do indeed harbor bacteria colonies - your tank may be relying on them for biological filtration as well.
Basically - don't clean everything on the same day.
