To first set you your saltwater aquarium, you should check your tank for leaks. You will then need to install your filteration system in your tank. You should then put in your plants. After you have done these steps, you can begin to fill your tank with clean dechlorinated water. You will need to use a hydrometer to measure the amount of salt is dissolved in the water. You should aim for 1.020 and 1.023 specific gravity. You will then need to add your heater and thermometer. You should let everything run for about 72 hours, and then you can add your fish.