Right now I am using a 100 with my tank. I do have a cup that I use as well when I run carbon in my tank then when its out or needs clean I put a sock in it and I have 2. the only one I really use is a 100 micron and the other is like a thin net. I just dont see the reason for the one that is like a net but it came with the tank. I think it is a 225 micron? I just wonder what others are running and what your reason is behind you using that one because I am about to buy another one and was thinking of going with something else.