I dunno why I missed this post.
What media are you referring to? The ceramic biomedia? You don't need to do anything with that unless it has gunk all over it, in which case you can rinse in tank water just like the filter pads.
As far as what the media does, I'm going to go by what the eheims normally come with and explain:
Fine polishing pads (the cottony looking ones) filter out small particles.
The course filter pads (the ones that have the texture more like a dish scrubber) filter out larger particles and also house biological media (the bacteria that filter ammonia and nitrites out of your tank).
The ceramic media mostly house biological bacteria and don't really do much particle filtration, other than breaking up some larger particles.
The amount of maintenance you do will depend on your bioload (amount of fish).
Tropicals or not, if you have a heavy bioload you will need to do it more often (only YOU can determine how often it needs to be done by researching the type of fish you have, feeding correctly, and checking how dirty your filter media looks. Testing your water will also help, since every time you have to do a water change (when nitrates get above 40 generally) you should check your filter media.)
If you feed a lot and have a heavy bioload you may have to do maintenance weekly even. If you have a small fish load and don't overfeed you may be able to go a couple of months without cleaning the media.
I'm not sure if you're starting out with an established tank or not, but if it is a new tank the biological media will need to be cycled. This means you need to add ammonia to your tank from some source (preferrably NOT fish! but if you already have them you can cycle with them, it will just be harder and definitely hard on the fish), check your water chemistry (ammonia, nitrite and nitrates), and wait for the biological bacteria to grow so that it can filter toxins out of your tank so you can properly house your fish. While cycling you will want to keep ammonia below .25, and nitrites below .25. When ammonia and nitrites read zero and you have nitrates present your tank is cycled and ready to house fish.
This is a simple explanation and if you need more info I can provide it.
Since this post is so old I'll assume your tank is already cycled or you have (hopefully not) killed your fish (not that I'd hold this against you if you're new...I think we've all done this accidentally at some time). Good luck.