Which part of the filter should I take from neighbour's tank to help with my new one? He has the same filter as I - there is a carbon part that is black plastic on one side, blue filtery stuff on the other and a small one in front that has white thick threadish kind of stuff. Do I take both? Just one part? I have to cycle with fish 'cause I have seen no pure amonia around here (and I have an anaphalactic allergy to shrimp!). I will have a seeded filter and start very slowly. My tank will only have tetras (black phantoms) and I was going to start with 3. They are very tiny. Thanks for any advice.