If you are new to betta fish and are unsure how often to change betta water, then this article is for you.
Ideally, you should perform a partial water change on your betta tank once a week, which will reduce ammonia and nitrite levels and help control the pH balance of your water. Smaller betta tanks may benefit from a partial water change every 1 or 2 days unless you have a suitable filter.
Many factors will determine how often you should change your betta water, such as:
- What is the tank size?
- How many fish are in the aquarium?
- How often do you feed your betta fish?
- Do you have a filter in your aquarium?
- Is it a well-planted betta tank?
You may also need to consider changing your betta tank water if you notice signs of stress or other health problems with your pet, which may be signs of environmental factors like ammonia or nitrate levels.
'Links on this page that lead to products on Amazon, Chewy, or other retailers are affiliate links and I earn a commission (at no extra cost to you) if you make a purchase. Huge thanks for supporting this site!'
Make sure to check out our Betta Fish Care Guide And Species Overview.
If you are unsure of exactly what you need, below I have added some links to the correct items available to buy online:
Gravel Siphon – (Find The Best Price At Amazon Or Chewy)
Water Conditioner – (Find The Best Price At Amazon Or Chewy)
Water Parameter Test Kit – (Find The Best Price At Amazon Or Chewy)
With all of the equipment ready, you will need to perform the cleaning process by:
- Removing your betta with a fish net to a clean container with some of the existing tank water.
- Remove the tank cover and clean thoroughly with a clean chemical-free cloth.
- Completely clean the entire tank with a cloth.
- Siphon the gravel, sand, or whatever substrate is at the bottom of the tank, into the clean bucket, removing no more than half the water and clearing any uneaten food particles and any other fish waste.
- Rinse the filter sponges under a tap or in the bucket of dirty water to remove any particles. Soak the sponges in the bucket before returning to the tank filter to ensure it harbors good bacteria.
- Dispose of the dirty water only when doing a partial water change. It holds beneficial bacteria and will need to be returned to the tank if doing a complete water change.
- Clean decorations and ornaments by rinsing them under a tap.
- Pour some tap water (or any drinking water) into the clean bucket. This is the replacement water.
- Slowly pour some hot or cold water into the bucket until you have warm water. Check the temperature and mix hot or cold water until you reach the same temperature as the tank water. (Use the tank thermometer to check)
- Add water conditioner to remove chlorine, other chemicals, and other harmful substances from the fresh water.
- Gently pour the fresh water into your betta’s tank.
- Wait for any substrate to settle and return your betta to the fish tank.
When changing your tank water, especially a large water change, try to ensure that the pH level of the new water is close to that of the existing tank water to avoid causing pH shock to your fish.
Any significant changes to your tank’s water chemistry that happens over a short time can cause shock, and pH shock is common during water changes. If you are unsure how to balance your pH, you can read this helpful guide: Fish Tank pH Levels (An easy guide for fishkeepers).
Well, that’s quite a list, so although changing betta fish water is not a difficult task, it can certainly seem that way. There is a lot to think about, and it can feel quite arduous when you have to do it once a week or even more frequently.
Some betta fish owners find playing music helps when they perform their weekly water changes or use the time to catch up on an audiobook or podcast. It’s important to keep your betta fish tank healthy, so why not make it more fun!
The whole process should only take 30 minutes, even quicker as you get used to it.
If you find that your fish tank water gets a little cloudy after a water change, it is quite normal and nothing to worry about. Cloudiness is often caused by a sudden bloom of good bacteria feeding on the loosened waste, or simply because of the disturbed sediment. Cloudiness usually subsides within a day.
If you haven’t already, why not read our article on Setting Up A Betta Tank. You may find some useful nuggets of information that you didn’t know.
How Often Do I Need To Change Betta Fish Water
Ok, so we have mentioned that you may need to change your betta water once a week, or maybe every day or two, and even longer in some cases, so exactly how often do you need to change your betta water?
As mentioned above, it is best if the tank can be changed every week with larger tanks being able to go longer in-between changes in a well-filtered tank without the risk of losing too much of the beneficial bacteria from the filter.
Good bacteria help keep ammonia, nitrate, and nitrite levels in check. It is a process called biological filtration, which will kick start the nitrogen cycle. By removing this water, you will also remove some beneficial bacteria.
It’s basically a fine balancing act. If the chemical levels in your tank are seriously out of whack, a full water change may be necessary, but that has some problems of its own and can cause much stress to your betta fish.
Partial water changes are the easiest and safest. You can easily replace up to 50 percent of the water in your tank without any problems arising, and you will mostly only need to perform a small 20 percent change.
It is always wise to have some water test strips and kits at hand so that you can check the chemical composition of your betta water without waiting for other symptoms to appear, such as sick fish.
How Often To Change The Water In A Small Tank
If you have opted for a small betta tank below 5 gallons, you will likely need to perform a small 20 percent partial water change at least every 2 days. Such frequent water changes are because a smaller body of water will become contaminated much more quickly than a larger body of water. I will also assume that you may not have a filter in such a small tank and, therefore, will need to do the job of a filter by hand.
How Often To Change The Water In A Medium Tank
A betta tank of around 5-20 gallons will need a water change once every week to ten days, although some may be able to go up to two weeks before needing a partial water change.
In this size tank, you may have a filter that will help to keep the water clean for longer without needing as many changes. You may also be able to go up to two weeks before needing a partial change if there are no other factors in play, such as high ammonia levels.
A 20-50 gallon betta tank can still be considered a medium-size tank but is pretty large in betta terms. A tank of this size can go up to 2 and maybe even 3 weeks without needing a partial water change, just don’t stretch it out too far and keep a check on the tank water quality.
How Often To Change The Water In A Large Tank
If your betta fish’s tank is 50 gallons or over, how often you change the water will depend on how many fish are in there, how much they eat and how long your tank has been set up. It is wise to still test the water at least once a week with your water test kits and change how often you need to accordingly. You may find that the tank will comfortably maintain itself for 3 or 4 weeks.
How Often To Change Betta WaterBest Conditions For Betta Fish
Ensuring that you have the best water conditions will go a long way to ensuring your betta remains healthy. Although betta fish can be quite fragile creatures, they can survive quite well as long as their environment remains optimum to live within it.
You can use a water test kit to check the water parameters regularly.
Betta Water Parameters At A Glance
The table below can be used as a quick guide to identifying the correct water parameters for your betta fish tank.
|Prefered Water Hardness|
dH (Degree of Hardness)
|Soft (dH less than 25)|
|pH (Power of Hydrogen)||Neutral to Slightly Acidic|
|Preferred Water Temperature Range||78° to 80° Fahrenheit, (25.5° – 26.7° Celsius)|
|Survivable Water Temperature Range||72° – 86° Fahrenheit (22.2° – 30° Celsius)|
What Temperature Do Betta Fish Like
The ideal water temperature for betta fish is between 78° to 80° Fahrenheit (25.5° – 26.7° Celsius). Bettas can live outside of these temperatures and can tolerate 72° – 86° Fahrenheit (22.2° – 30° Celsius), but they will not feel comfortable, and it can affect their health over a prolonged period.
Is Tap Water Safe For Betta Fish
Tap water is safe for betta fish to live in as long as the water is treated properly. It’s important that if your tap water has any chlorine or chloramines present, these will need to be removed before adding the water to your tank.
If there are chemicals such as mercury in the tap water, these can also be harmful to your betta fish, and using the correct treatments, you can help reduce other minerals and heavy metals that are present.
Ideal Betta pH Range
Betta fish prefer to live in softer water with a neutral pH level of around 7, although they can tolerate a slightly more acidic level of 6.5. It won’t matter too much if the pH level is a little off, providing it is consistent, you should be just fine.
If you want to learn a little more about pH levels, I have written a great article that will teach you everything you will need to know as a fishkeeper: Fish Tank pH Levels (An easy guide for fishkeepers).
Essential to the ongoing health of your betta fish tank, and to keep your betta healthy, frequent cleans and water changes should not be thought of as a chore and put off.
Without these cleans, your tank is likely to become a toxic environment. Regular water changes and a clean tank will help your betta have a healthy happy life and will increase your betta’s lifespan.
If you are planning on doing a more intensive clean, and you have stains, grease, or calcium deposits that are difficult to remove, I have an excellent article that explains how to use a vinegar solution to get your tank looking squeaky clean: How To Clean A Fish Tank With Vinegar (In 9 easy steps).