Hi gang. I have had a 10 gal for over a year, so I'm kind of an "experienced " noob ! I do need some help, tho. I just bought a 46 gal bowfront and purchased an Emperor 400 bio wheel filter for it. I 'm getting it set up and I see there are 4 slots for filter media prior to the wheels. The 2 slots on the left were empty, and the 2 on the right had empty filter media holders. The ones on the left had a bag with 2 charcoal cartridges (size E) that I assume go in the 2 slots ? What goes in the 2 media holders on the right side ? Can someone tell me what goes where ? Thanx for the help. I guess I should have asked at the store, but I figured (incorrectly, it turns out !) the directions would help me. The pet store is 50 miles away or I'd go ask them ! Thanx again.:newbie: