I'll look into that. I have 1/2 a tray free (thin 300ppi sponge in top tray), perhaps replace a blue sponge with carbon. Then back in once the carbon has done its job.You can always run an absolute tonne of carbon in the filter for 30 days. This will really help with water quality during the early stages.
Is it worth considering using some of the "wool" I hear about? Throwing it away afterwards (not very Eco though).
Best,
Brian