powerheads

I've never tried flourite, but I think it will cause problems. The filter would be enough, but you will want to set-it up in reverse flow configuration, not conventional. I personally would still run a secondary filter for extra mechanical, But that is the way I do things.
dave

I'm with Dave, never tried Flourite but think some pcs would at least get wedged in the spaces of the plate. I would also go with Reverse flow. As for 2 powerheads...depends on what size. You don't want to run 2 400gph heads, but there are enough sizes to fit your need. If you're running 2 in a Reverse flow set up, you wouldn't need an extra mechanical filter (IMO) since you could turn one off, rinse the filter, replace, turn off other, rinse filter, done. If you do run reverse flow, heavy root feeding plants may not do well with your set up.