Filter media question?

When I first bought my Juwel aquairum about a year ago the instructions for setting up the filter system sponges were as follows and even included an initial set of sponges (order from inlet to outlet)

Polypad

Carbon

Nitrate removal

Coarse sponge

2 x fine sponges

I have been changning the sponges as recommended.

However recently i have notice that Juwel have been producing a sponge sized box containing balls so that the bacteria has surface area to grow on

I've seen these in other filtration systems but i presumed that the fine blue sponges were doing that job in the Juwels instead.

I have space for one of these in my sponge baskets but is it worth adding or maybe even replacing a blue sponge for? Obviously the more living space for bacteria the better but is it worth putting money up for this, will the quality of the water increase at all when the blue sponges already do that work?

If it's worth adding where in the chain of sponges should it sit??