Start a saltwater tank
with confidence.

1. Choose your tank and inhabitants

Decide whether you want fish only, fish with live rock, or a reef with corals. Research adult size, temperament, compatibility and minimum space before purchasing livestock. A larger tank generally changes more slowly than a nano tank, though it costs more and still needs regular care. Use a level, sturdy stand rated for the full weight of water, rock and equipment.

2. Gather the essentials

Plan for filtration and biological media or suitable rock, a heater and separate thermometer, circulation, a lid, saltwater test kits, marine salt mix, a calibrated refractometer or salinity meter, and clean mixing containers. RO/DI water is a common choice to limit unwanted contaminants. Reef animals need appropriate lighting; a protein skimmer or automatic top-off can be useful depending on the setup. Choose equipment for the tank and livestock, not just the advertised tank size.

3. Mix and measure your saltwater

Use a marine aquarium salt mix—not table salt—and follow its directions. Mix in a clean, dedicated container with circulation; check temperature and salinity after the salt has fully dissolved and stabilized. A common reef target is around 35 ppt (specific gravity approximately 1.026 at the meter’s calibration temperature), but match the requirements of your animals. Calibrate the meter according to its instructions. Never add dry salt directly to a tank containing animals.

When water evaporates, the salt stays behind. Replace evaporation with fresh RO/DI water, not saltwater. For water changes, prepare new saltwater separately and match temperature and salinity.

4. Cycle without fish

The nitrogen cycle establishes microbes that process ammonia into nitrite and then nitrate. Use a measured ammonia source and a fishless cycling method, following the product directions. Test ammonia and nitrite throughout; freshly mixed water reading zero does not mean the tank is cycled. Confirm that the system can process a measured ammonia dose with ammonia and nitrite returning to undetectable within the protocol’s specified period, commonly 24 hours. Cycling often takes weeks; bottled bacteria may help but is not proof of readiness.

When the cycle is complete, change water as needed to reduce nitrate, and verify temperature, salinity and other parameters appropriate to the intended species before adding livestock. Never dose cycling ammonia with animals in the tank.

5. Add livestock gradually

Start with a small, compatible first addition after the cycle is verified. Quarantine and observation can reduce the chance of introducing disease; research a practical quarantine plan in advance. Acclimate according to the supplier’s directions, and give the biological filter time to adjust between additions. Test water frequently during stocking. Corals and invertebrates have their own care and water chemistry requirements; add them only after researching their needs.

6. Make maintenance a habit

Observe animals daily, check temperature and evaporation, and test salinity and water chemistry regularly. Perform appropriately sized water changes, remove accumulated debris, and maintain pumps and filter media without stripping all established biological media at once. Record your results and make gradual corrections. A stable routine beats chasing perfect numbers.

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