Filter media

I was hoping someone could give me an idea about the differences between -
ammo lock - zeolite - nitrazorb - purigen - or anything else in this general
family? I don't know how they work. My primary interest is inevitably
reducing nitrates. Ammonia and nitrites are never a problem. But, I don't
know whether the ammonia products keep the nitrate cycle from completing.
And of course any opinions about the desirability and effectiveness would
also be appreciated.

I have 2 Penguin 330's, a 2 basket off brand canister, and a Mini Aqua Clear
which I could add something extra to. One of the 330's + the canister are
probably my main concern, as they are in the Fancy GF tank which always has
by far the highest nitrates. The 330's do have little baskets behind the
filter mats which something can be added. Currently in those I am just
adding the cheap poly batting filter floss stuff.

I do weekly water changes and already use Prime Plus, which purports to help
reduce nitrites and nitrates as well as de chloraminating (is that a word
My tap water comes complete with Ammonia and Nitri/ates.
Thanxx
Bill