costs of running carbon and Phosban/GFO

[Fishward]

hey,
just trying to put together a bit of a lifecycle cost for running carbon and phosphate media in 2 reactors. i figure i can get 2 reactors for about $100, and pumps for another 60 or so? what sorta media replacement costs are there? how much is the stuff? how often would i have to replace it on a 85 gallon system? can you run two reactors on a single pump? advisable? any tips would be awesome!