Care
Feb 21, 2026
How long should new saltwater mix before a water change?
Quick Answer
Most reef keepers should mix and aerate new saltwater for 12 to 24 hours before use to stabilize pH, temperature, and oxygen levels.
For most reef systems, mix new saltwater for 12-24 hours before a water change.
Why this window works
- Salt fully dissolves and stabilizes chemistry
- pH and alkalinity settle before dosing to display
- Temperature can be matched to 77-79°F
- Aeration improves oxygen and CO2 balance
Fast prep checklist
- Use RO/DI water in a clean bin.
- Add reef salt slowly with strong circulation.
- Heat to display-tank temperature.
- Confirm salinity around 1.025, then re-test before use.
Calculator CTA
Use ReefBay’s Water Change Calculator to project nitrate/phosphate reductions before you swap water. In the app, jump to /app/calc-water-change for quick calculations during maintenance day.
Need supplies? Browse salt, heater, and pump options on ReefBay.
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