I used to use a full blown zeo system, and still use a partial system currently. Like any other bacterial nutrient export system, it relies on bacterial biomass to lock up N and P, which is then exported via skimming. The bacterial reproduction is pushed with some sort of energy source or limiting nutrient (usually a carbon source), and supplements are used to encourage coloration once the system becomes "low nutrient" or "ultra low nutrient"
There are many different similar systems out there (prodibio, polyp lab, fauna marin, etc). I have seen tanks that have great SPS coloration with and without such systems. It's by no means the only way to reduce nutrients, but it does work.
JMO!