Maintaining your nano reef is a very important task, and it can be quite simple. Usually you can do all of your maintenance in 15 minutes or less. The most important part of maintaining your nano reef is doing partial water changes. Water changes must be done religiously! You can do your partial water changes every week to every other week, depending on the bio load in your tank. If you decide to do them weekly, change out 10% of the tanks volume with freshly mixed saltwater. If you do them bi-weekly, then you will need to do a 15-20% water change. To save time, you will want to keep saltwater already mixed in a 20 gallon container, so when the time comes to do a water change, you will always have mixed water on hand. Also, make sure that the water is the same temperature and salinity as the water already in the aquarium.
Next to water changes, evaporation top off is also very important. You may have to do this daily depending on the size and shape of your aquarium. Evaporation top off is simply adding freshwater to your aquarium to make up for the water that evaporates throughout the day. Remember to never use saltwater to top off evaporation, because the salt is left behind during evaporation and your specific gravity will rise.
You will also want to be wiping off your nano reef with freshwater to keep it clean of salt creep. Salt creep comes from the salt left over from the evaporated water. You will notice it collecting on the top of you tank and on the lights. Be sure to never use a chemical cleaner! If any of it were to get into the aquarium, it could kill everything.
If you have algae growing on the sides of your nano reef, you will need to clean that off as well. If you have a glass aquarium, you can use a straight edge razor and scrape it clean, or if you have an acrylic aquarium, you can use an appropriate acrylic-safe scraper. If you use the razor, be sure to rinse it off after you use it, because the saltwater will corrode the metal.