Glenda,

The bio filtration of an Emperor is in the bio-wheels. You don't need more in the chambers, which are designed for mechanical filtration, with charcoal and zeno in the baskets and pads to trap coarse and fine particulates behind the baskets.

You also don't need to spend piles of $ on replacement cartridges. Just order up another pair of baskets and use the flat edged top part as a frame to hold bonded filer pads cut from a bulk roll and hold them on with rubber bands. With the front media baskets filled, you really don't need more charcoal or zeno in the back frames holding the pads.

The pads don't need to be cut to fit perfectly either; just close enough to cover. I cut mine in 6 x 8 inch increments and they fit fine. If you can find the bonded media in a 12 inch width, it makes pad cutting easier. Just measure every 8 inches, cut, then split in half lengthwise and you have both pads. The bonded media is particularly good because it offers both coarse and fine particulate traps. Mount the coarse, white part out, to the back of the filter and hold it onto the frame with rubber bands at the top and bottom.

You can even reuse the pads. They will rinse pretty clean under a strong spray and again, they are strictly for mechanical filtration so cleaning them has no impact on the bio-filtration of the filter- as long as you never allow the bio-wheels to dry out and clean them occassionally by swishing them in tank water.

However, if you really don't want to bother, for replacement cartridges, both standard and fancy, check out:

kensfish.com, Big Als, or Foster & Smith.