The Fluval x05 series are, I think, mechanically better than the Magnum (I have a Magnum 350, a Fluval 205, two 305's, and a 404). The Fluvals prime
much easier and the Magnum is prone to impeller wear if you suck up fine grain sand. The disconnect for the Fluval hoses is much better (easier to disconnect, less water spilled).
I don't use the ceramic media in the Fluvals on
SW tanks (I use them on both
FW and
SW). I load my
SW Fluvals with floss, carbon, Purigen and
phosphate sponge.
The Magnum is a great filter for water polishing, as Carmie said, with the micron paper cartridge. And you can load it up with
diatom powder, if you want. I use my Magnum to suck up suspended
detritus whan I stir the sand in the
SW tanks and to vacuum out the
sump. I got the gavel vac attachment for the Magnum and use that for cleaning our
FW substrates. It works super for that.
I am glad I have both.
