I agree with not overcleaning your external filter except for. If you are using carbon to remove medication or ammonia/nitrate/Nitrite pads, if you leave these too long they can release the contaminats back into your water. be sure to read the instructions.
This is my 300ltr Discus tank, lightly planted with Amazon swords , 2 pcs of bog wood , filtered by a Fluval 407, internal power filter with only floss and a sunset surface skimmer.
It is my entry for tank of the month.