How Often Should I Test My Reef Tank Water Parameters?

Regular water testing is essential for maintaining a healthy reef tank. The frequency depends on your tank's maturity, bioload, and what you're keeping. Here's a practical testing schedule for most reef aquariums.

Weekly Testing (Essential)

These parameters should be tested at least once per week:

• Salinity – Target: 1.024-1.026 (35 ppt)
• Alkalinity (dKH) – Target: 8-11 dKH
• Calcium – Target: 400-450 ppm
• Magnesium – Target: 1250-1400 ppm
• pH – Target: 8.0-8.4

These are the "big five" that directly impact coral health and growth. Stability is often more important than hitting exact numbers—consistent parameters are better than perfect but fluctuating values.

Bi-Weekly Testing

• Nitrate – Target: 5-20 ppm (some tanks do well with ultra-low levels, others need some nitrate)
• Phosphate – Target: 0.03-0.1 ppm

These nutrients affect algae growth and coral coloration. High levels can cause algae outbreaks; too low can starve corals.

Monthly or As-Needed Testing

• Ammonia – Should always be 0 in an established tank
• Nitrite – Should always be 0 in an established tank
• Iodine, Strontium, Potassium – Only if dosing these elements

Test ammonia and nitrite if you notice livestock stress, after adding new animals, or if something seems off. In a healthy, established tank, these should always read zero.

New Tank Testing Schedule

During the cycling period (first 4-8 weeks), test more frequently:

1. Daily: Ammonia and nitrite
2. Every 2-3 days: Nitrate, pH
3. Weekly: Everything else

Once the cycle completes (ammonia and nitrite consistently at zero), you can transition to the standard weekly schedule.

Testing Tips

• Test at the same time – Parameters fluctuate throughout the day; consistency helps spot trends
• Keep a log – Track your results over time to spot problems early
• Calibrate equipment – Refractometers and probes need regular calibration
• Quality test kits – Invest in reliable kits (Salifert, Hanna, Red Sea are popular choices)

The ReefBay app makes tracking parameters easy—log your test results, see trends over time, and get alerts when values drift outside your target range. Consistent tracking helps you catch small problems before they become big ones.

When to Test More Often

Increase testing frequency if you:

• Added new livestock
• Changed your dosing routine
• Notice coral stress or bleaching
• Had an equipment failure
• See unexplained algae growth

Remember: testing is only useful if you act on the results. Identify trends, adjust your maintenance routine, and your reef will thrive.