Do you feel the new roller filters will work in a similar way? The roll has 25 micron holes that block up slowly filtering finer and finer, until the mechanism triggers to advance the roll... sounds like they will catch the free swimming stage CI to me..I have used pleated micron filters to filter out the free swimming stages of CI. Well, I have used them, and the infections went away over time. I only have anecdote to support this, but the reasoning checks out.
I used nu clear canisters with 25 micron pleated filters, as they get dirty they get more efficient and filter out smaller stuff, so fluffing the sand in the display flocs the filter. Since the free swimming stages are like 18 micron, over a month or two it stands to reason that the filter would be filtering out that size particle. The canister was run off a mag 8, and pulled water directly from, and returned to, the 200 gallon display in which CI was showing up, but catching the fish out would have needed the display to be broken down. This was in conjunction with our vet. CI popped upu twice more in the first month, very few dots, and then didn't show up anymore. This was 4 years ago.
If the fish are healthy and eating and difficult to catch out, this would be my first step.