Fliter Media Question

[MMAX]

I have a Fluval 305 cannister type filter on my 20 gallon. It contains 2 foam pre filters, 2 carbon packs on the bottom tray, 1 carbon pack and biomax ceramic rings in the middle and the top are biomax ceramic rings. I was told by the salesman to run the carbon while the tank is cycling but to remove it when you add animals because they need nutrients that the carbon may remove. I took the single carbon pack out of the middle tray and put a foam pad in its place but still have both carbon packs in the bottom tray. Any comments or suggestions on carbon filtration or any other type of media I should be running in my filter would be greatly appreciated.
P.S. I've also heard of taking all the media out of the cannister (foam pre filters and all) and putting in live rock. Comments on this?

[TNTCanada]

Foam pre filters can be very efficient for trapping particles in the water cullum but they need to be cleaned very regularly as they will trap all the nasty stuff and start decomposing creating Ammonia and then nitrates and nitrites.... as for carbon ...yes it can take some of the elements that you are wanting to keep in your tank... but with regular water changes you should be fine... but they all so have some good qualities.... I run carbon all the time as I have corals and corals can decide to have chemical warfare on each other... some can be very toxic... as well it does help with polishing your water to keep it crisp and clean and help with odors... depending on how much live rock you may have in your system and the BIO load in you tank will depend on what you may need if you have a very small BIO load you may not need to have a filter besides the live rock and water changes...

Just some thoughts