Calculators / Water change
Aquarium Water Change Calculator
Enter your tank size and the percentage you want to change.
5.0 gallons
Remove and replace 5.0 gallons (18.9 liters). At the common strength of 1 mL of conditioner per 10 gallons, that is about 0.5 mL for the new water. Strengths vary, so follow your bottle's label.
See gravel vacuums on AmazonWater change questions
How much water should I change in my fish tank?
For most freshwater tanks, about 25% once a week. Heavily stocked tanks and tanks with messy fish such as goldfish do better with larger or more frequent changes.
Do I need to treat tap water before adding it?
Yes. Tap water usually contains chlorine or chloramine, which harm fish and the bacteria in your filter. Add water conditioner to the new water, following the dose on the bottle.
Should the new water match the tank temperature?
Yes, as closely as you reasonably can. Aim for within a couple of degrees to avoid stressing the fish.