How Often Should You Change Water In Aquariums?

If you’re new to fishkeeping and are trying to determine how best to maintain your aquarium water, you may feel overwhelmed by the amount of factors you need to consider.

Fish are delicate creatures that need a stable environment, and how you choose to change their tank water can deeply impact their health.

This guide will help you to understand how often you should change water in your home aquarium so you create the safest and cleanest space for your fish to thrive.

Consider the contents of your fish tank

Before deciding how often or how much water you should change in your aquarium, consider what kinds of fish and how much you have in your tank. 

Do you have messier fish in your tank, like Koi Carp or goldfish? How many fish are you keeping in your aquarium, and how often are they fed? 

More frequent feedings and messier fish mean more waste, so it may benefit you to change their tank water more often. Always remember, though, to research and understand the fish in your tank before deciding on a cleaning schedule.

How much water to change in an aquarium

It is more beneficial to change tank water more frequently in smaller amounts. This is because the delicate pH levels in the water need to remain as consistent as possible for your fish to stay safe. 

Anywhere from 5-25% of tank water should be changed regularly, depending on the size of your tank, plants, and number of fish. 

A common rule to follow for standard-sized tanks is to change about 10% of your tank water every week or about 25% of your tank water every two to four weeks. This allows your fish to have water that’s frequently refreshed without disturbing the life-sustaining flora inside.

No matter how often you change the water, the amount you change should remain below 50% of the tank water at a time. Anything more than this can risk depleting nitrogen levels drastically and completely disturb the good bacteria built up over time, ultimately proving fatal for your pets.

How to change aquarium water

●       Turn off the filter system.

●       Use a syphon and begin draining the amount of water you will change. Do not remove your fish.

●       Use the suction from the syphon to pick up any waste sediments or debris on the gravel of your tank.

●       Take a clean new sponge or algae pad and wipe down the glass of the tank.

●       Clean your filtration system[1]  and replace your filter cartridge if necessary.

●       Take fresh water and use a de-chlorinator or water conditioner to safely prepare it for your tank.

●       Add your dechlorinated water little by little into the aquarium to refill your tank. 

●       Replace the filter system and turn it back on.

Fish tank water maintenance tips

After you’ve prepared your new water to add back to your tank, make sure it’s the right temperature to keep the environment consistent and not stress out your fish.

Some aquarists use a tank heater to ensure their aquarium reaches the proper temperature.

Leaving water unchanged for too long can promote harmful algae growth that can make your fish sick. Create a schedule that works for your bio load in your fish tank. 

Finally and most importantly, no matter how dirty your tank is, do not attempt to do a 100% water replacement for your aquarium. Fish need a thriving environment with healthy bacteria that have built up over time, and a sterilised water system is a toxic water system for fish. 

If you have questions about how to properly maintain your home aquarium, speak with our water filtration experts here at Finerfilters.