Water Change Calculator

Calculate resulting water parameters after a partial water change.

Results

Visualization

How It Works

Water changes dilute pollutants like nitrate using the formula: New Level = (Old x (1 - %changed)) + (Tap x %changed). A 25% water change reduces nitrate by roughly 25% of the difference between tank and tap water. Most freshwater tanks need 25-50% weekly water changes to keep nitrate below 40 ppm.