Just to add...somewhere in this post someone mentioned seachem's denitrate...it is rendered useless in terms of denitrifying in high flow areas....there is a specified flow rate mentioned in the packaging in order for denitrate to work....
in my opinion..get the bigger sized Seachem Matrix....its bigger..meaning there are deeper microcavities in the *pebbles* for denitrifying bacteria to get into deeper areas....and its meant for canister usage (ie. good for fast flow areas)
I am using Seachem's Matrix, Coralife's Nitrate Controller, Seachem's Purigen...to combat the nitrate problem that is unresolved after protein skimming...