Water Change Calculator
How much water to change and how often.
How to Use the Water Change Calculator
Enter your tank size in gallons and the desired change percentage (25% is standard). The calculator shows exact gallons and liters to remove and replace.
Common Uses
- Preparing the right amount of treated water
- Scheduling a consistent maintenance routine
- Reducing nitrates in heavily stocked tanks
Frequently Asked Questions
How often should I change aquarium water?
Most freshwater tanks benefit from a 25% water change every 1–2 weeks. Heavily stocked tanks may need more frequent changes.
What percentage should I change?
25% is the standard recommendation. Large changes (>50%) can stress fish by rapidly changing water parameters.
Is this tool free?
Yes, PetCalc is free.