So I just got and set up my new XP3. Now the box comes with two filter media pieces, which is fine with me, and all the parts are in there. But the manual says something about having multiple zorb-chem packets or whatever. And sure enough on the packet it says for up to 55g. Well, my tank is 150g and are they expecting me to buy another 2-3 packets or do I have this all wrong; someone help?