You can usually buy the micron filters at the LFS
, but www.petwarehouse.com
has better prices. If you want to buy locally, just have them order you the o-rings. I only use the micron filter occassionally, to clean up the water. Everyday I use the canister as a biological filter filled with media to grow bacteria, you'll need the filter sleeve to go over it.
I run a Magnum 350 and a set of bio-wheels on my 70 gal
tank. I like having two filters -- don't have to worry if one ever goes out and it keeps the tank cleaner.
If you're thinking about getting a bio-wheel, definitely check out www.petwarehouse.com
(Dr.'s Foster & Smith). They'll send you a free catalog (and they send it pretty quick too.)
If you have any questions or problems with the Magnum, feel free to e-mail me. I don't check here very often.