Availability of a good population of special bacteria is absolutely vital for a natural filtering function, and thus reduction of nutrients. In nearly every reef tank this is done by so called “live rock” (LR). LR is natural reef material from dead corals which is taken out of real reefs or special LR breeding stations. Lots of different bacteria life on the surface as well as in the extremely porous inside of LR, which is optimum room for bacteria growth. Exactly this is giving the biologocal filter base of LR which will change from Amonium -> Nitrite -> Nitrate -> Nitrogen -> clear water.
Quality of LR that you use for your tank is absolutely decisive for a good running tank!
You can also use dead rock, that will also be populated by bacteria, for parts of your reef. Also this should be real rocks from dead corals not “normal stones” to get populated by bacteria. Establishing bacteria population takes much longer for dead rock. Using reef ceramics is about the same as using dead rock in terms of bacteria population.
Adding LR will also bring other inhabitants of the reef to your tank. Most of it are good, but you have no guarantee that not also some unwanted items come to your tank (crabs, mantis shrimps, aiptasia, unwanted algae like Bryopsis, …). During transport, which is done only “damp” because of cost reasons, some inhabitants of LR are killed. Added to your tank, thus LR need some days of start up and where they regenerate themselves.