Starting a saltwater aquarium

Mix and measure

1. Mix synthetic sea salt into dechlorinated fresh water with circulation until fully dissolved.
2. Measure salinity with a calibrated refractometer.
3. Match temperature and salinity before any water goes into the tank.

Cycle with real verification

• Suitable mature media, live rock or a bacteria product may seed the biofilter. An ammonia source feeds those microbes; it does not supply them.
• Prove it with ammonia and nitrite tests, as in the cycling guide. A marine cycle is not reliably faster or slower.
• Maintain circulation. Follow the cycling product’s instructions for skimmers and other equipment.

Rock is part of the filter

• Colonized rock brings bacteria, plus organisms you did not choose and decaying material.
• Dry rock avoids that but starts with no bacteria, so it needs the full cycle.
• Build it stable on the tank floor, off the glass, with room for a siphon and net.
• Removing lots of rock at once is a biological event. Stage it. See substrate and hardscape.

Keep the salinity reading honest

• Follow the exact instrument’s calibration instructions: some require distilled or deionized water; others use a specified salinity standard.
• Rinse and dry it after use; note when it was last calibrated.
• When a reading surprises you, check the instrument before the water.

Expect a longer runway

• Add hardy, well-researched species first, one at a time, testing after each.
• Wait until readings have held steady for a while before coral or delicate fish.
• Consistent testing and a written record beat any single piece of equipment. See reef tank basics.

Budget honestly

• Budget for salt mix, water preparation, salinity measurement and suitable filtration. A protein skimmer and specialized lighting depend on the animals and system.
• Check filtration and waste-removal needs for your stocking plan before choosing equipment.
• Every water change uses salt and prepared water, so budget for them on an ongoing basis.