IMO, I would look into a better
skimmer, or other methods of dealing with
nitrate. I understand denitrators are difficult to get up and running just right, require constant tinkering, and may not be all that effective. It's gotta run for a while to establish colonies of anaerobic bacteria, and if you push too much water throug it, and you get oxygenated water down to the bacteria, you have to start all over again.
Have you considered growing macro, or a
DSB, or even a remote
DSB? It sounds like your
sump is plenty large for a nice
fuge with
DSB and macro in it.