In my opinion, A skimmer is not a necessity for this size tank, especially at this age as it’s just starting out. Will it hurt the tank to have one, no, but once you are on your way small water changes will be your best bet for any pollutant reduction. With that being said. Take it slow,
and enjoy the beginning stages of life in your reef. It’s an awesome hobby and you can achieve great results by learning the basics. Try not to get caught up in the hype machine with the corals and equipment. You chose a solid tank that can bring you years of enjoyment! Last but not least. Have fun, everything is a learning experience you will get algae, pest, loose corals and fish. It happens to the best of them. Just keep learning