I have the CurrentUSA AquaPod 24 and the Tunze Nano skimmer just fits in the first compartment of the filter. I'm not sure about all 24 Nano's as I believe some have 3 compartments instead of 2. As far as the Current Fission skimmer, it is worthless. The collection cup is way too small and difficult to remove and clean without changing the position of the base. In addition, it did not skim well either. IME skimmers are not an area to skimp on price if you plan to use one.
One problem I have had is maintaining the correct water level for the skimmer. In my case, I replaced the sponge behind the filter intake with fibre floss and the water level in the filter compartment tends to vary over the week due to evaporation and gunk in the fibre floss. This occurs even with daily addition of RO water to account for evaporation. I have fixed the problem some by removing one of the intake doors and pushing the fibre floss down so some water can flow freely over the top of it.
The main reason I bought a skimmer is for vacations when I have someone feeding the fish who may put too much food in the tank. In general, it does not remove a lot of DOC weekly, but I still run it as nitrates have started to build now that the tank is 10 months old and I figure anything it removes is better than nothing.
Hope this is helpful.