Dialing in reef tank parameters is the difference between struggling to keep coral alive and watching your reef grow and color up. For beginners, the challenge isn’t just knowing the ideal numbers, but understanding which parameters truly matter and how to keep them stable over time.

Core Reef Tank Parameters for Beginners

While there are many things you can test, beginners should focus on the core group that has the biggest impact on coral health and algae control.

Salinity

Target salinity: 1.025–1.026 specific gravity (35 ppt)

• Use a refractometer calibrated with proper calibration fluid, not tap water.
• Top off evaporated water with fresh RO/DI water, not saltwater, to keep salinity stable.

Temperature

Target temperature: 77–79°F (25–26°C)

• Avoid swings larger than 1–2°F in a day.
• Use a reliable heater and consider a backup or controller for safety.

Alkalinity, Calcium, and Magnesium

These three work together to support coral skeleton growth.

• Alkalinity: 8–9.5 dKH
• Calcium: 400–450 ppm
• Magnesium: 1250–1400 ppm

For a new tank with light coral load, weekly water changes often maintain these levels. As corals grow, you may need to begin dosing; see our guide on reef dosing basics for step-by-step help.

Nitrate and Phosphate

Contrary to old advice, a little nitrate and phosphate is healthy for corals.

• Nitrate: 5–15 ppm
• Phosphate: 0.03–0.10 ppm

If these are zero, corals may pale and slow their growth. If they climb too high, you’ll battle nuisance algae. Feeding less, improving filtration, and regular water changes help bring them into range. Our article on controlling nutrients in a reef tank covers this in more detail.

Testing, Stability, and Simple Routines

Knowing the target numbers is only half of the equation. The real key is stability.

How Often Should Beginners Test?

• Weekly: Salinity, temperature (daily glance), nitrate, phosphate.
• Weekly at first, then biweekly: Alkalinity, calcium, magnesium.

Keep a simple logbook or spreadsheet. Seeing trends over time is far more useful than a single reading.

Tips for Keeping Parameters Stable

• Mix saltwater the same way every time: Same brand, same salinity, fully mixed and heated before water changes.
• Avoid chasing numbers: Don’t swing parameters rapidly with big corrections; adjust slowly over days.
• Automate what you can: An auto top-off (ATO) system is one of the easiest upgrades for stable salinity.
• Stock slowly: Adding fish and coral gradually prevents sudden jumps in nutrient demand.

For a complete new-tank checklist, including testing gear and salt mix suggestions, take a look at our reef tank setup checklist.

Remember: a slightly imperfect but stable reef is far healthier than a tank with “perfect” numbers that swing every day.

As a beginner, focus on these core parameters, test consistently, and make slow, measured adjustments. Over time you’ll learn how your specific system behaves, and maintaining ideal reef tank parameters will feel less like guesswork and more like routine care. That’s when your reef really starts to thrive.

Sources

• Borneman, E. H. Aquarium Corals. TFH Publications.
• Sprung, J., & Delbeek, J. C. The Reef Aquarium series. Ricordea Publishing.
• Holmes-Farley, R. “Reef Aquarium Water Parameters,” Reefkeeping Magazine.