Filtration advise for my new tank

Hi all,

As you may have read in my previous post, I am purchasing a new tank in the
new year and I'm looking at making some improvements on my current setup.

I my current tank, i notice a lot of film on the top of the water and today
when I was at the LFS, there was a 4x2x2 with a corner over-flow. I was
wondering if I could use this to fill with media and then have it running
off to my eheim 2217 canister filter..?

I was thinking of filling it mainly with mechanical filtration materials and
then have it run out to my canister for the main biological filtration, thus
maybe doubling my biological surface area, which would be a plus with the
discus...

I have done some reading on the net and the only mention of this type of
set-up, as most have a sump set-up, is that the canister filter has to have
it's motor at the bottom for some reason...?? If i maintin the water level
high enough in the overflow setion, this would not break the siphon down to
the canister filter and it should work right?

It would remove the dead plant leave that float on my water and would also
hide most of the filtration equipment so it wouldn't distract from the main
thing - the plants...

I was wondering if anyone has any advise re this, or have done a similar
thing and can give me some hints/tips?

thanks in advance.

Justin.