This may sound odd, but I tried the string/air tube method to keep my floaters away from the filter, but it never worked due to evap and water level changes.. this is what I did:
Ya know them there betta logs they sell at petco/petsmart .. my betta liked his but for a short time (I have since switched to dwarf water lettuce) I tied my betta log to my Tetra 10i filter (my betta has 0 problems with it) with fishing line (through the top hole) and let the water pour into the hole at the top... INSTANT BAFFLE .. worked like a charm... too well... duckweed,... everywhere. I since scraped out all the duckweed and went with a larger floater and gave him back his log. Might be a cheap addition.
If you buy one, scrub it with a new toothbrush to get the dust off.. the paint on those aren't quality..