Welcome to the forum! I have a 2215, which is similar, just slightly larger than yours. The filter can use a variety of media. I can't remember all the trademarked names, so I'll describe the various options for filter media (ordered from bottom of canister to top):
1) The ceramic "tubes" - used as the bottom (first) layer on the bottom plastic insert to trap large particles and serve as a bed for bacterial growth. Basically anything in the filter has bacteria growing on it!
2) Blue coarse filter pad - used to separate layers, trap smaller particles, and as a bacteria bed
3) Small glass/ceramic spheres (don't remember the material) - Adds a HUGE amounts of surface for bacterial growth and thus accelerates waste decomposition.
4) Blue coarse filter sponge - keeps the spheres in place and see #2 again.
5) White fine filter pad. Final layer of very fine media that traps smaller particles that may have made their way through the coarse blue pads.
- You can use 5 of the coarse blue pads (I think it's five?) instead of the ceramic tubes and spheres. Just top with the white fine pad. It works well, I've done that sometimes.
-Inexpensive option: use some generic filter floss purchased on-line and fill the canister with it. Good results, low cost of replacement!
- other less expensive option for ceramic disks/tubes. Use another manufacturers brand, other brands are cheaper!
AVOID: using the carbon pads, unless it's a new tank setup or you are trying to remove medications or other chemicals from the tank water.
Ok, that's the basics. Now the set-up usually comes with a carbon pad. IF you are using the filter on a brand new tank, follow the directions about using the carbon filter. Use it for a couple of weeks and pull it out. If you are adding the canister to an existing tank, don't use the carbon pad, keep the old filter running and wait a couple of weeks before removing the old filter. This gives time for bacteria to establish in the canister.
Cleaning: Some folks here only clean their Eheims every couple of months. I wish I could do that! I have to clean mine every couple of weeks due to plant material and slime build-ups in my intake lines and canister. You can make it a lot easier by using mesh bags to hold the ceramic media (the type of plastic mesh bags that your Christmas ham or turkey may have come in). The mesh bags make it much easier to remove the loose media when cleaning. I recommend purchasing a long brush to clean the intake lines once in a while. Put the hose quick disconnects, if you ahve them, in the middle of the hoses so each hose section is not too long to clean out using the brush!
Here is a great link for cleaning info:
Eheim Classic Canister Cleaning Instructions
Good luck and enjoy the filter!