How much water should you swap?
Regular partial water changes are the simplest way to keep waste from building up and to keep your fish healthy. Enter your tank volume and how much you plan to change, and we'll tell you how many litres of fresh water to prepare and how much dechlorinator that new water needs.
Match the temperature. Get the new water close to the tank's temperature before you add it - a sudden cold or hot slug of water shocks fish more than the change itself.
⚠️ Treat and age your tap water for chlorine and chloramine before it goes near your fish - both are added to drinking water and both are harmful to fish and to the good bacteria in your filter. Always follow the dose printed on your own dechlorinator bottle; the default here is only a common example.