Most people typically start with small all in one aquarium for their first. For many reasons such as budget, space, and to figure out if they even enjoy the hobby. Those are great reasons to start small but the vast majority of people end up upgrading to a much larger aquarium within the first year of being in the hobby. This is why we typically advise starting with a 60-120-gallon aquarium. This will end up saving you money in the future because you will not be spending the money to upgrade. The second reason it is a better idea to have more water volume to start with is with saltwater aquariums things can change quickly as far as water parameters go. With more water volume you have a more stable aquarium that will be more resilient to beginner mistakes.