get seachem matrix for the media in it, that's independant of water flow.
just as a side note, for the discussion of water changes.
i know a guy, who had 400 some gallons in his system, between a 125 tank, a refuge, a sump, and a frag tank.
he's got the best coral tank i've ever seen, there's probably more coral than water in the main tank. seriously i have yet to see any better on the net or wherever.
he only does 10% wc
's once ever 4 months.
just something to think about.
i think it's the refuge/sump combo more than anything else but /shrug