[Myka]

I have a sulphur denitrator that works quite well with an ORP monitor on a fish only system. I wouldn't recommend it to novice reefers (or reef tanks) as it can crash a tank if used without an ORP monitor or if left unchecked. I wouldn't use it on a reef tank just because reefs seem to be easier to crash than FOWLR or FO tanks. It's the sort of thing you need to pay attention to...not set and forget. It is also quite a pricey piece of equipment, plus the ORP monitor isn't cheap either. Works like a hot dang though.

I haven't heard of any other denitrators being particularly effective. A good skimmer and good maintenance practices are the best long-term solution in my opinion - especially for reef tanks.