the tank size is a 75G, just got it too, i bought the filter on ebay very cheap, i did some research on them before i bought, a lot of people really like them and they are made by eheim, even use the same trays and all, everything is interchangeable for the both of them. i think i have it working properly now, the intake hose kept shifting in the back of the tank by the wall, i've went ahead and cut it down to a better length, so its not kinking up , as far as the skimmer they sell those on, i think it was big al's, i dont remember if they termed it a protein skimmer or just a top skimmer, now the only thing not getting sucked up is just on the surface of the water, i decided to check the pull on the intake side, i took off the little strainer and put my hand on just tube and its definately got suction now, maybe if it runs properly overnight, no kinking etc., it will eventually get the debri that is on the surface, like the debri will get pushed around by the bubbler current, and will get sucked up. when i put the media in, i put zeo-lite on bottom, the rings, then carbon, then sponge, maybe i should change the order their in, similiar to yours, it makes more sense that i might need to change carbon before i would the sponge or ceramic rings, this is the first canister i've ever dealt with, so sorry for all the questions but i'm grateful for all the suggestions/thank you so much for your information, your patience, and tolerance with my questions!!