Reef Tank Parameters: The Ideal Ranges
6 min read · TankBase
Corals are unforgiving of swings. A pH crash overnight or a salinity spike from evaporation can stress an entire tank. These are the numbers to aim for, and the ones to never let drift.
The big six
Temperature: 25–26 °C. Stability matters more than the exact number.
Salinity: 1.024–1.026 SG (35 ppt). Use a refractometer — hydrometers drift.
pH: 8.1–8.4. Lower at night is normal.
Ammonia: 0 ppm. Anything above means a die-off somewhere.
Nitrite: 0 ppm.
Nitrate: 1–10 ppm for SPS, 5–15 ppm for mixed reefs, 10–25 ppm for LPS and softies.
Coral chemistry
Alkalinity: 8–9 dKH for stability. Drift no more than 0.5 dKH per day.
Calcium: 400–450 ppm.
Magnesium: 1300–1400 ppm. Without enough Mg, calcium and alkalinity precipitate out.
Phosphate: 0.03–0.08 ppm. Zero phosphate starves corals; high phosphate fuels algae.
What to test, how often
Daily: temperature, salinity (with an ATO running).
Weekly: alkalinity, calcium, magnesium, nitrate, phosphate.
Monthly: send a sample to an ICP test service such as Triton, ATI or Fauna Marin for trace elements.
Log every reading in TankBase Tank Log — trends matter far more than single values.
Track these parameters automatically
TankBase Tank Log charts every reading you take and flags anything out of range — free to try.
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