Trying saltwater
 

Hello i am gonna try and start the world of coral reef aquarium. For starters i was looking at a jbj 28g nano cube. Are they any good? And what else would i need for supplies?

29 is a good starter:
#1-Dry Rock, there are a few hitchhikers on Live Rock that people want to stay away from, so they opt for using Dry Rock, or Dead Rock. Macro Rock is a good place to start looking for that. Either way you go you will need a minimum of 1lb per gallon.
#2-Replacement filter media like filter floss and activated carbon (if you get a filter) Which is really not necessary.
#3-Multiple Power heads (2 or 3) 10x your water volume for just a Fish Only With Live Rock, and at least 20x your water volume for a Reef Tank. So lets say your going reef, and you have a 100g tank, you would need flow in that tank at minimum of 2000gph, or 2 1000gph power heads.
#4-Protein Skimmer, rated at 2 times your water volume
#5-Saltwater Test Kits. Reef Test Kit. Test for Ammonia, Nitrites, Nitrates, PH, Phosphates, Calcium, ALK and Magnesium.
#6-Saltwater fish food. Mysis Shrimp, Squid, Cyclopease, Algae Sheets, Romaine . Flake food is not really a good food to feed your marine fish.
#7-Aquarium vacuum. This one is iffy. Most don't use one, if you have enough flow in the tank you won’t need one
#8-Rubber kitchen gloves
#9-Fish net
#10-Two, clean, never used before, 5-gallon buckets
#11-Aquarium thermometer, digital being the best.
#12-Brush with plastic bristles (old tooth brush) - needed for cleaning the live rock if you don't get Fully Cured Live Rock.
#13-Power Strip, possibly GFCI outlets by the tank.
#14-Optional but definitely recommend getting a Reverse Osmosis or RO/Deionization filter for the make-up water, and a barrel for storing the water.
#15-Possibly a Quarantine Tank for your new fish. They sit in here for a few weeks to kill off parasites and bacteria, to keep it from getting in your main tank
#16-Heater rated for your size tank.
#17-Saltwater Mix. Marine Salt. Instant Ocean is the cheap Salt that beginners and Advanced use alike.
#18-Saltwater Hydrometer or even better a Refractometer, which is more accurate. There is also a Digital Meter that is way advanced if you have the cash.
#19-Aquarium filter (not absolutely necessary if running with adequate amounts of live rock, but nice to have if you need to use a mechanical filter or activated carbon, or GFO and such)
#20-Aquarium substrate such as live sand or crushed coral. Some go bare Bottom, others choose the 2-3" bottom, others, more advanced will try the Deep Sand Bed, which is over 6" deep.

Where are you at in this process? On a tank this size I would personally use a 4'' sand bed, aragonite reef grade sand, with 10 pounds live rock, 25 pounds dry rock, and a hang on protein skimmer. The maintenance will be pretty easy on a tank this size. Livestock selection will be the challenge, so don't set your hopes to high, just approach this as getting your feet wet to learn about the marine hobby.

If you can afford more, I'd recommend a 38 or even a 55 gallon if space allows.