Honestly, if you don't know, then the answer is 'its too hard.' Reefs are another world compared to freshwater, and nano reefs are even harder to maintain than larger systems. It can be done, but I found out that the time and cost it takes to maintain saltwater would be the equivalent of maintaining 4 medium freshwater tanks.
I'm not trying to shoot you down, just trying to help you see the end result. I USED to maintain 2 saltwater tanks and 3 freshwater tanks. I now maintanin 10+ freshwater tanks and spend less money, time and energy keeping them going. I know other people in the club in the same boat.
Starting saltwater means new types of food, chemicals, lights, buffers and other various items. Every time you run out of one thing it means another trip to the store or online order. Most of the supplies I have for my freshwater tanks can all be used on every tank.
Just my 2 cents, but an honest opinion.