Are you set on SunSun? While many have had solid experience with them, there's little to no support beyond the point of purchase. So if something breaks, it's up to you to resolve it.
Filters from companies like Eheim and Fluval cost a bit more up front but are also covered under warranty and replacement parts are relatively affordable and easy to find. For a 20gal long, you should be able to get a great filter for $100-ish.
As far as the Fugeray, you won't encounter massive algae issues without CO2 but would definitely be better off having it. Using a couple pieces of fiberglass window screen between the light and the tank will allow you to remain in the low light range. Without the screen material, you'd only be at about 50ish PAR. That's enough for a little bit of algae if your photoperiod is too long. I use the 30" fixture for six hours per day on a 20L and have no algae issues.