🔄 Water Change Calculator
Plan your water change schedule and calculate exact volumes needed.
Optional — for nitrate reduction estimate
Results
Water Change Volume
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Per water change
In Liters
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Monthly Total
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Nitrate Reduction
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Change volume = Tank gallons × Change %
Post-change nitrate = Current nitrate × (1 − Change%/100)
Reef: 10-15% weekly. Freshwater: 20-30% weekly.
Post-change nitrate = Current nitrate × (1 − Change%/100)
Reef: 10-15% weekly. Freshwater: 20-30% weekly.
Water Change Guide
Regular water changes are the foundation of aquarium health. They dilute nitrates, phosphates, and dissolved organics while replenishing trace elements.
Recommended Schedules
| Tank Type | Change % | Frequency |
|---|---|---|
| Reef (SPS/LPS) | 10–15% | Weekly |
| Reef (Soft/FOWLR) | 15–20% | Bi-weekly |
| Freshwater | 20–30% | Weekly |
| Planted Tank | 30–50% | Weekly |
Dilution Math
A 10% water change reduces nitrate by 10%. To drop nitrate from 40 ppm to 10 ppm requires multiple changes: after a 25% change you'd go from 40 → 30, then 30 → 22.5, then 22.5 → 16.9. Consistency matters more than volume.