Every tank should have Purigen!!!!I have a pre-filter tray and 2 trays of biomax.
I would return the zeo-carb if you still can. I bought it too, and never ended up using it! Its still sitting under the aquarium in the stand...
The zeo-carb is good for controlling spikes in parameters, but it can clown your cycling. If you want something to help, but won't slow the cycle, I heard Purgien does both! I haven't used any myself, but I've heard nothing but good things.