There are a number of reactor additives; De-nitrate, Nitrazorb, nitrate reducer, purigen, as well as other non-resins such as GFO
that create a place for anaerobic bacteria to consume nitrate (and produce nitrogen gas).
Resins use a chemical bonding process whereby a resin will bond to the nitrogen atom in all forms of nitrogenous waster (amm, nitire and nitrate).
If your nitrates are elevated, I would also suggest Nitrate destroyer, a bacterial additive that eats nitrate and then dies, being consumed by corals, pods
and skimmer out in a skimmer. Once your nitrate levels fall you can discontinue using it.