When you say floss, I assume you mean the loose, fluffy stuff rather than denser sheets that you can cut to shape? If you have intakes to something with a strong pump that you can wrap some pretty dense foam or filter pads around, it should help with sudden abundances of fine particulates. It's always worked for me with the annoying dust storms that result from new sand and sudden hermit crab digging parties. If you have any powerheads with a small, wrappable intake, those work great to stick a small bunch of filter pad onto with a rubberband for a while. I find that covering the intakes tends to work better than putting the same material just about anywhere else like in a HOTB or canister chamber, although I don't have a sump to test whether a gravity-based flow would work as well.