The thing with nitra-zorb is, it has a very short use life before it needs to be recharged.
when you are setting up a tank nd getting a bacterial filter going, dont use it. If at some point after your cycle is done, you get a spike in nitrate/nitrite/ammonia you can use it to quickly knock down the ppm count.
But the bag only works for about 24 hours then its "full" and needs to be cleaned/recharged.
Also recharge it in distilled water, if your tap water contains any nitrate/nitrite count at all.
and, the bag will get organic waste built up in it which you cant really get rid of so you should put in in water flow that is CLEAN.
24 hours, recharge, repeat. Dropping it in a canister or hanging it in the tank for a week is useless. It MUST be recharged ever 24 hours, when it is exposed to a good flow rate.