Bettas are gorgeous fish that swim around their tanks like kings of the castle, but how often should you change betta water?
Many factors influence how often to change betta water, such as the filters, tank size, and any live plants. Generally, you should partially change the water every week and change most of the water once a month. Never change the water completely, as this disrupts the tank’s nitrogen cycle.
Below is everything you need to know about how often to change betta water and why it is important, plus a step-by-step guide on easily changing the tank’s water.
How Often to Change Betta tank Water
If you’re used to changing a fish tank’s water all at once, you may be surprised that betta fish tanks are different. Your betta will thrive with small, more frequent water changes because it maintains a stable water condition.
Betta fish tanks should have a partial water change of 20% every week, with a 75% change done monthly. You should never change more than 75% at one time, as this can disrupt the nitrogen cycle in the tank.
Factors like filters, tank size, and live plants can affect how often you need to change the water.
Why Should You Change the Water Regularly?
Over time, your betta’s water can fill with waste, leftover food, and decaying plants. As these things break down, they can cause the ammonia levels in the water to rise, creating a toxic environment for the fish.
As bacteria break down the ammonia through oxidation, they will create nitrate NO2 and NO3. NO2 is toxic to fish, while NO3 is non-toxic in low concentrations. If you have plants in your tank, you need NO3 to keep them healthy, so a low ammonia level is okay.
However, if you don’t have live plants in your tank, you want to prevent as much ammonia as possible because nothing will break down the NO3, leading to high toxicity levels.
5 Factors Related to Water Change Frequency
It’s easy to say that you should do a 20% water change every week, but there are a few reasons why that schedule may not be the same for every betta tank. The filter, size of the tank, live plants, feeding frequency, and the number of fish in the tank can require more or fewer water changes.
The Filter
Not all fish tanks require filters, but I recommend one if outfitting a betta tank. Sponge filters work best in small tanks with well-established ecosystems that don’t need a lot of water flow. The filter can help beneficial house bacteria.
Without a filter, you’d need to do a partial 20% water change weekly. With a filter, you can do a partial change every two weeks. This extra week is excellent for anyone with busier schedules that still want to enjoy bettas.
Tank Size
You’ll need to do fewer water changes with larger tanks. Bettas have a recommended tank size of at least 3 gallons, but I prefer to keep mine in a 10-gallon tank. I use the larger tank for a few reasons.
For one, the ammonia levels at parts per million (ppm) will be smaller and easier to control with a larger volume of water. This larger size allows me to do fewer water changes, which benefits my fish. They don’t like water changes any more than we like cleaning their tanks!
I also believe that a 10-gallon gives my bettas enough room to be comfortable. It helps that I keep live plants in the tank, which I’ll discuss next.
Plants
I will always encourage you to have live plants in all fish tanks, no matter what type of fish you’re keeping. Live plants help keep the nitrate levels low and aid in the tank’s nitrogen cycle (something that’s normal and will happen no matter what).
Some plants will help remove harmful bacteria while promoting good bacteria. I have a mixture of java ferns, moss balls, and water sprites. All three are extremely easy to care for. The water sprite is an excellent location for your betta’s bubble nests.
You should still do weekly water changes when you have live plants in the tank. With live plants, you can do larger water changes because the plants will help balance out the nitrogen levels in the water. However, you should never do more than a 75% change at one time.
Feeding Frequency
Since leftover food is one of the ways ammonia can build up in the tank, you’ll need to keep an eye on how much food your betta isn’t eating. More food in the tank means more ammonia and more frequent water changes.
The Number of Fish
When you have more than one fish in a tank, you’ll have to do more frequent water changes because the fish produce more waste. Because bettas are usually solitary, this factor won’t impact your tank as much as the previous four.
If you have multiple bettas in one tank, you should stick to the once-a-week water change, even if you have a filter, live plants, and a low feeding frequency.
How To Change the Water: A Step-by-Step Guide
There are two standard methods to change a fish tank’s water. In the first method, you don’t need to remove the betta while changing or cleaning the water. This method requires you to be careful while cleaning, so you don’t injure or frighten your fish.
The second method is to move the betta and 80% of the original water into a different tank or container. In this method, you can deep clean the tank and empty it of water. It can be more difficult if you have live plants.
In addition to the second method, you can move the betta to a different tank (with enough original water to keep it happy) and then do a standard 20% water change on the tank. This method combines methods one and two but still requires you to remove your fish.
Step 1: What You’ll Need
To change the water, you’ll need the following:
- Siphon hose
- pH test kit
- Thermometer
- De-chlorinator/water conditioner
- 2 large buckets
The siphon hose enables you to remove debris from the bottom of the tank and easily remove around 20% of the tank’s water. The pH test kit is essential, as bettas prefer water to be a neutral 7 (though they will survive in 6.5 to 8).
You’ll use the thermometer to ensure the water is the correct temperature for your fish before you replace it (75 F to 80 F). The de-chlorinator and water conditioner ensure the water isn’t toxic to your fish.
Knowing where your water comes from is essential. If you have tap water, you’ll want to use the de-chlorinator or allow the water to sit for 24 hours before you add it to the tank. If you have well water, you’ll need a water conditioner. Well water can contain heavy minerals you don’t want in your fish tank. Never use distilled water.
The buckets are for the water you’ll be removing and replacing.
Step 2: Unplug Everything
Before moving water around, ensure that all electrical components are unplugged and away from sockets. You don’t want your fish tank to electrocute you!
After they’re unplugged, you can take out any tank decor items you want to clean. You can clean them with a sponge, but I use an old toothbrush for getting into the small nooks and crannies.
I recommend you clean or replace your sponge filter once a month. You can save part of the original sponge to help maintain the beneficial bacteria growth.
Step 3: Clean Tank Thoroughly
Whether you have your fish in a different tank or still living in its home, now you’ll want to start thoroughly cleaning the tank. This step is when you’ll remove your water (whether 20%, 30%, etc.).
Clean the tank walls with a sponge to remove algae or dirt, then use the water siphon to remove particles on the bottom of the tank. Avoid your betta during this process, as the siphon can damage its fins.
I typically use the siphon last. While I’m cleaning the decor and scrubbing the sides of the tank, debris will fall to the tank floor. You don’t want to start with the water siphon and clean the bottom only to clean the rest of the tank and need to siphon the bottom again.
Step 4: Fill With New Water
You can use your treated water to fill the tank back up to capacity. You can use a ladle or carefully pour the water from a bucket. Be gentle, so you don’t injure or shock the fish.
Depending on where you live, you may be unable to dump the dirty water down the drain. Some municipalities can’t treat it as effectively as others. My recommendation is to water your indoor and outdoor plants! The old tank water is full of nutrients.
Step 5: Turn Everything Back On
Now that everything is clean and the tank is full, it’s time to plug everything back in and turn everything on! You can replace the decor, turn the heater, lights, and filter back on, and place the tank cover on top. Congratulations! You changed your betta’s water.
In Conclusion
You should do a partial change of around 20% once a week with a 75% change once a month. Adding live plants is a great way to keep dangerous nitrate levels down, and adding a sponge filter can help beneficial bacteria thrive.
