When I had the internals in both my juwel tanks I was very happy with them, water was crystal clear and there was more than enough media inside. I only removed mine to add more space as it's a big tank.
You could move all the media, and if like mine it has two holes inside the filter casing where water is sucked out, then block the top one, then fill a nylon stocking with sintered glass so it fills almost all the filter, then put the Green pad on top with a fine floss ontop of that. Flow then goes through all of it before being pumped back out. If not, then add a bigger pump to it. I have two 1000 l/hr pumps spare for the jewel if it fits your welcome to one for a donation to ukaps.
And another note, the green nitrate sponge may seem a waste of time, but once it's in it's aiding in more surface area for bacteria! I never replaced any of my sponges