io gallon nano do I need a skimmer?

Depends on your load would depend on your desire for a skimmer and also your wallet size:) . even with a skimmer a 10% weekly water change, in my opinion, is always a good thing to do.
you most definitely dont NEED a skimmer on a 10 gallon, espically if you already know you will need to do weekly water changes, but as these guys have said, if you can swing it, it will make your maintenance that much easier.
I do weekly water changes in mine and have never had any trouble. I also only have one fish and a bunch of soft coral.