Yes, but it takes a large amount. When you use Xenia to control your nitrates, they are called "Xenia Scrubbers". A study was done a while back about how much Xenia actually consumes and what it consumes. It most likely is linked in Randy Holmes-Farley's forum. All in all, your single best removal of nitrates is water changes, followed by algal scrubbers, deep sand beds and live rock. Most of the latter are found in your typical "Refugium" set up.