DSB in a bucket for nitrate control

[32flavors]

oh man, what a thread!! I apologize for what I'm sure is a redundant question--I've read much but not all of this thread...

I have a 120 I'm moving into...

Will a 5 gal bucket filled to 5" from top do it?

What is the recommended GPH through there, and would it be adviseable to have this in a stage say right after my Coil Denitrator but before the skimmer which I use for re-O2ing water before return to tank?

Flow:

overflow to safety chamber (I've seen some small fish Yashe Hashi, Blue-spot Watchmen end up in overflows, so I don't use a sock), thru 6 layers floss, to Coil Denitrator, sits in sump in case ever starts to leak, gravity dump to 2nd sump to LARGE macro chamber (CO2 rich CD water good for plants), to last chamber where water is skimmed before return. There's also a phosphate reactor I'm not using as my PO4 is zero that I'm toying with turning into a Sulphur Denitrator--it's back by the Coil denitrator.

What do you all think?