A Nano Cube is a special type of aquarium, typically available in sizes around 20 to 24 gallons, that is set up to house a tiny saltwater ecosystem like a coral reef. It comes with several materials to make setting up a saltwater aquarium easy, including special lighting, filters and a protein skimmer. However, setting one up requires care, attention and several more materials that you'll need to purchase at your local pet store. Most of all, however, setting up a Nano Cube aquarium requires patience.
Place your aquarium in an area where it will not be exposed to direct sunlight, like a basement. Keeping your aquarium out of areas of direct sunlight will help to keep algae from overgrowing in your tank.
Fill the tank with fresh water until the water is about 1/2 inch below the top of the tank.
Add the marine sand to the aquarium. Much of it will float to the surface, so keep it submerged until all of the sand sinks. If you want, you can mix the sand in with some water in a bowl until it's thick; it will sink to the bottom much more easily.
Add all of the marine salt to the tank's water and stir with the mixing spoon until it completely dissolves.
Test the salinity of the water using the hydrometer. Submerge the hydrometer until it fills with your aquarium's water, then take it out and lay it onto a flat surface. The tiny plastic needle in the hydrometer will then point to the specific gravity of the water.
Adjust the salinity level of the aquarium water needed for your fish accordingly. If the specific gravity is above .0025ppt (parts per trillion), you may consider diluting the tank with freshwater to lower the salinity level. If it's below .0020ppt, then you will need to add more salt.
Test to ensure that the items in your aquarium work. Place the aquarium heater in your tank, as well as your thermometer, and turn on and off the lights.
Add the appropriate dosage of dechlorinator to the aquarium. The appropriate dosage will vary according to the dechlorinator's manufacturer.
Turn on the filter, protein skimmer and aquarium heater, and allow the tank to cycle for at least two weeks, turning on the lights during the day and turning them off at night. Test the water daily during this time to ensure that salinity levels remain consistent. Replace any water that evaporates.
Test the water using the saltwater test kit, making sure that you have the appropriate ammonia, pH and other chemical levels. The correct levels will depend on the types of animals being put into the aquarium (though most saltwater fish require a pH level around 8.0-8.5), so make sure you consult with a pet store employee before testing your aquarium.
Place a small test fish in your aquarium. If it survives a week, then obviously your aquarium is prepared to accept coral and more fish.
Instead of mixing the saltwater yourself, it may be a better idea to buy the water premixed from pet stores. Premixed water is a safer alternative to mixing it on your own. Add a cleaning animal to your tank after about a week, like a turbo snail or a hermit crab. It will help clean up any algae that starts to bloom in your tank.