ULNS - Denitrators

[b09u5]

What's the best option for keeping Nitrates near 0?

I have been cruising the web for ways to limit nitrates in my setup. I like the idea of ULNS, but don't like the idea of Zeovit for two reasons (I could be very wrong, so please correct me): by targeting the ammonia/ammonium, the tank is effectively not cycled, meaning there is no easy way off the system without a cycle/crash; dosing unknowns without testing and watching for changes to corals is not measurable enough to give me any sense of comfort.

As I understand it, this leaves few options if I want to keep nitrates near 0.2ppm: huge daily water changes; deep sand bed; bio pellets, carbon/coil denitrator, or a sulfur denitrator.

I have tried to find out why sulfur denitrators went out of style, or never caught on in the first place. If anyone can help me figure this out, I would appreciate it. I can't find too many down sides to them, aside from having to monitor pH, dose Alk, and keeping an eye on ORP values on the aquarium and effluent as a method of monitoring the viability of the bacteria within.

I can anticipate similar potential issues with the bio pellets (unstable and aerobic makes potential crashes more likely) and the carbon/coil denitrators (require specific dosing of a carbon source), but still don't understand why they haven't caught on as well?

If anyone can shed some light on this, I would greatly appreciate it.