Converting a Tank to Saltwater

We're eventually going to be converting my 20 gal into a mini SW tank. I've been reading online and can't come up with a consensus... would we need a protein skimmer? It would be a FOWLR

For a tank that small and fish only i would say no. just keep up with your water changes and you will be fine.

As said above, for a fowlr you won't need a skimmer if you keep up with your water changes! I would recommend getting an aquaclear filter and find one of the surface skimmer attachments for it. That's exactly how I have my 50g fowlr setup and it works well. It goes against everything I do with my full blown reef tank, but it's nice to have a simpler system for the fish! With some t5 or LED lighting, you could keep zoanthids and some other softies in there as well. You'll get hooked!

A protien skimmer will make your life easier by reducing the size/frequency of water changes. It will eventually pay for itself in reduced salt mix/real sea water costs.

But is it necessary? No.

If it was a bigger tank i would agree. but any skimmer i have ever seen small enough to fit a 20 gallon was pretty much worthless.

Ok, and LED lights are fine? I've got them on the current FW set up we have now.