So, I'm starting to get the itch to jump into saltwater aquariums. I'm just here to ask a million questions and get my equipment list and stock plan together well in advance. I know it is advised for a beginning saltwater tank to be larger, but I'd really love to try a 20 gallon long. I'm interested in inverts, blennies, gobies, and maybe some very small reef safe fish. I am open to all suggestions regarding livestock and corals, and equipment. I want good quality but also don't have unlimited resources. I'm also looking for recommendations and general info on RO/DI systems as I've never used one before. If possible, I'd like to do a Hawaiian biotope, as my son's father is from Hawaii and it would sure help me to explain setting up ANOTHER tank, haha. I have 4 aquariums, all planted freshwater. A 3.7 gallon, a 5.5 gallon, a 10 gallon, and an 85 gallon with sump and automatic dosing pump for ferts. I use all LED lighting. I'm hoping that some of this experience will translate well and help ease me into saltwater. If you were trying to set up a 20 gallon long reef Hawaiian biotope, with attention to inverts and bottom dwellers, what sort of things would be a must buy for you?