What to put in my canister filter - Rena XP2

One or two trays (the most "downstream" trays) will generally have some sort of media as a "home" for the beneficial bacteria... rough ceramic rings, balls, pellets are commercially available... but anything that will stay in place and provide lots of surface area will work. (These never get replaced, and allow a place for the bacteria to live, so you can replace the fiber filter pads every couple months without worrying about spiking the ammonia.)

One tray with activated carbon if you like that. (the most "upstream" tray)

Remaining trays stuffed with a polyester "floss" of some sort... expensive (designed for that purpose) stuff from the LFS, or cheap stuff from the fabric store... you can pack it in fairly tightly (as long as water can still be pushed through it) to provide whatever level of fine-filtering you desire.

There really is no "one right way" to use a canister... a lot depends on personal preferences and the tank and the water you're working with.
 
It all depends on your tank set up.
 
use that foam/sponge media and now either put the Hagen ceramic rings in there or if those don't fit for w/e reason then use Eheim's Substrat Pro.

Personally thats all I run on my canisters...you should really only add active carbon when finishing a med treatment of clearing out driftwood tannin..
 
I was checking out the Hagen BioMax and it said that it needed to be replaced every 3 months. That doesn't seem right. I thought the idea was to leave them in there to keep the bacteria up.
 
I believe that's a sales gimmick. I've had the same ceramic rings for over two years now. I think they are indestructible. Just rinse them at each filter cleaning. :)
 
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