I just setup my SunSun/Perfect HW-404B, 530 gph (the new upgraded model from the HW-304B). I was able to fit 3 filter pads in the bottom basket and 4 liters of matrix and one more filter pad in the upper baskets. The canister fired up right away with just a few pumps of the priming pump, really easy. For the money ($100 shipped) these filters seem like a good buy. Also they are dead silent. Here is a pic: