Floss or no Floss

[grouper25]

I have elected to buy a sulphur denitrator to rid my tank of nitrates which approximate 80ppm in my 220. I have a 45 gallon sump, MRC2 skimmer and Aqua 40 w UV and a large bio load. I also use a Fluval X5 cannister filter(860 GPH) which I have only kept floss in as carbon is in the sump. The Fluval does an amazing job at polishing my water. It is absolutely crystal clear with zero particulate matter floating around. However, given where the filter is located and the time it takes to open and clean it, it is not something I desire to do each week as I do with the sponge blocks in my sump.

So the question is this. I am concerned that the build up of waste on the floss that is in the Fluval, assuming I currently change the floss every 60 days , is contributing to my nitrate problem, irrespective of the new denitrator I will be adding. I love what the Fluval does and am not losing it. Therefore, should I continue to use floss in it or pack it with some of the Ehiem small substrate?
In either case, I am not sure which option will have greater efficacy in minimizing nitrates.

Thanks Mates