That's kind of what I was getting at in the last post...
Again depending on how and with what the fuge is set up (and it's effective size) it will remove nitrates from the system....however..
If it's too small the effect may not be noticeable or measurable....
If it's just "marginal" ..it may only be able to keep them from "rising" rather than lower them...
If there are other factors (nitrate producers) working against it it may not be able to keep up...
If other "good husbandry" techniques are not employed (good skimmer, low bioload, adaquate clean up crew, regular partial WCs, etc..) effectiveness will be compromised...
On the other hand, I have my tanks set up with large sumps, larger "Algal Scrubber" fuges, Killer skimmers, occasional carbon runs, and adaquate LR...and have "0" algae problems in either tank..."0" nitrates in the reef and consistantly less than 15 in my 210 Aggressive which has Large fish, minimal clean up crew (they keep getting eaten) and is fed about a 1/2 lb of "meat" a week...