Care
Feb 9, 2026
How Often Should I Do Water Changes in My Reef Tank?
Quick Answer
Most reef keepers do 10-20% water changes weekly or bi-weekly. The ideal frequency depends on your bioload, filtration, and coral demands—test your water regularly and adjust accordingly.
A good starting point is 10-20% water change every 1-2 weeks. However, the "right" frequency varies based on your tank's specific needs.
Factors That Affect Water Change Frequency
- Bioload: More fish and feeding = more waste = more frequent changes
- Coral demands: SPS-heavy tanks may need more consistent maintenance
- Filtration: Tanks with refugiums and quality skimmers can go longer between changes
- Tank maturity: New tanks often need more frequent changes than established systems
General Guidelines by Tank Type
- Fish-only tanks: 15-25% every 2 weeks
- Soft coral tanks: 10-15% weekly or 20% bi-weekly
- Mixed reef: 10-20% weekly
- SPS-dominant tanks: 10-15% weekly (consistency is key)
Signs You Need More Frequent Changes
- Rising nitrates or phosphates
- Algae blooms
- Corals looking stressed or pale
- Fish showing signs of illness
Water Change Best Practices
- Match parameters: Temperature, salinity, and pH should match your tank
- Use quality salt: Choose a reputable reef salt mix
- RO/DI water: Always use purified water to avoid introducing contaminants
- Siphon the substrate: Remove detritus while you're at it
- Clean equipment: Good time to wipe down powerheads and overflow
Track Your Water Changes
Use the ReefBay app to log your water changes and track parameters over time. This helps you find the optimal schedule for your specific tank.
Pro tip: Consistency matters more than volume. Regular 10% weekly changes often work better than sporadic 30% changes monthly.
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