nice lights.
A cannister filter sits outside the tank, and gets water pumped through it, passing through media on the inside, like carbon, sponges, etc. Generally speaking, you don't need one for a reef, although some people use them for carbon.
A cannister filter sits outside the tank, and gets water pumped through it, passing through media on the inside, like carbon, sponges, etc. Generally speaking, you don't need one for a reef, although some people use them for carbon.