The filter media should be cleaned in dechlorinated water with each water change. This removes most of the solid wastes before they can break down and add to the ammonia levels, without damaging the bacteria beds. I do not replace the sponge media in my tank until it is literally falling apart--for my AquaClears, this means about 6-9 months, depending on the tank. I have 2 sponges in my 300's, so I can replace one, wait 2-3 weeks, and replace the other. I do weekly water changes, so the sponges usually stay fairly clean.
For bio-media, like noodles and bio-balls, it's best to either have a pre-filter so solid waste don't make it into the media, or run some clean water through the media with each water change to wash out any solids.
You do not want to just remove all the bio-media, either noodles, sponges, pads, etx at once--this will remove much of the biological filtration for the tank and most likely result in a mini cycle as the colonies catch up to their former size.
