Learning how often to change the water in your betta tank, and how to change it is the most important factor in the long term health of your fish. High ammonia and nitrate levels caused by waste aren’t visible but can seriously stress out and cause harm to you bettta.
This article will explain exactly how often to change your betta fish water, as well as in very clear steps exactly how to change your water without harming your betta fish. A video is also included to demonstrate the cleaning process.
How Often To Change your Betta Fish Water
It depends……..yes – not the answer you were looking for. All of the factors below contribute to how frequently your water needs to be changed:
- What is the size of the tank
- Is it a filtered tank
- Is the Betta Fish alone or are there others in the tank
- Did you cycle your tank when you initially set it up? (If you are unsure of what this is then its a no – if interested see Aquarium Nitrogen Cycle)
- Have you been over-feeding your fish? The amount of uneaten food rotting in the bottom of fish tank helps create toxic ammonia in your tank rapidly decreasing the water quality.
General Rules of thumb for how often to change a fish tank
- If you keep your Betta in an unfiltered bowl then you should change 30-50% of the water every week – the smaller the bowl the more water you should change.
- If your Betta lives in a filtered tank then you only need to change out about 20% of the water each week.
The real goal is to make sure the ammonia levels in the water are still safe for the fish, as rotting and decaying food turn into ammonia which is toxic to fish.
You may want to consider also getting some test strips which quickly evaluate your water quality to let you know if conditions are safe or in need of a change. You can find strips like these at Amazon, Petsmart or any fish store.
Items you will need for the water change:
- 1 (or 2) buckets
- 1 clean bucket to hold the new water that will be added to the tank. Important: make sure it has never had any sort of cleaning chemicals in.
- A 2nd bucket for the dirty water, doesn’t need to be clean as its getting dumped. You can even water your plants so even a watering can will do
- A tank cleaning siphon – special siphon for draining water from a fish tank while also letting it “vacuum” the waste from the bottom – all without seriously stressing out your fish. Video below in the article of the exact siphon I use and a video on how to use it.
- Water conditioner – used to remove the chlorine from the tap water in your house. You can find water conditioner at just about any pet store and online like Tetra BettaSafe Water Conditioner.
- Tank thermometer (which you should already have) – to make sure the new water is the right temp before adding back in
How to change betta fish water in your tank in 3 easy steps:
Now, you don’t simply dump out a bunch of water and dump new tap water in, right? Of course not, that would seriously stress out your Betta Fish.
Step # 1 – Remove the Old Water
All of these steps are done without removing your Betta Fish. These are gentle steps that aren’t too disruptive to your fish. The only time you should need to remove your fish is for a full water change if something drastic went wrong with the tank water.
- remove the tank cover – make sure any filters, lights or heaters that are plugged in no longer is as a safety measure.
- get the ‘catch’ bucket close to the tank
- remove any decorative items like large rocks, houses, etc from the bottom of the tank
- place the suction tube or hose into the tank – some tubes have a way to get the water flowing in a siphon action simply by letting it fill with water and then shaking it lightly. If you don’t have one of these you’ll have to do it the hard way and give the end of the hose not in the tank enough of a suck to get the water starting to flow up and out. Make sure you pull it away from your mouth and put it in the catch bucket before it hits your lips!
- Drag the suction hose across the tank gravel – what you are doing here is somewhat bobbing the the hose up and down across all of the gravel in your tank at a 45 degree angle. The reason you are doing this is it will suck up and remove rotting uneaten fish food that is collecting in the gravel, which will help make for a healthier tank.
- Make sure you don’t remove too much water – only remove the recommended amount mention above based on your tank setup. The remaining water in the tank has necessary beneficial bacteria in it necessary for a healthy environment. Once you are done removing the tank water you can dump that water down the toilet.
Step #2 – Prepare the new water
You can start this step either at the time of cleaning or prior:
- Fill a very clean bucket or container with water –
- use the “clean” bucket” that can hold up to the amount of water you need to replace in the tank. I use the same clean container only for this purpose, so its never confused as a cleaning bucket for household chores that may contain some sort of toxic residue from cleaners
- As you fill try to gauge the temp – you want it as close to 78 degrees if possible. Use your thermometer to test the temp. Add warm or cool water as needed to get the temp just right.
- Treat the water with water conditioner – our tap water is full of things that aren’t good for fish like fluoride and chlorine. Water conditioner will take care that, and it can easily be found at any pet store
Step #3 – Add the new water to the tank
- Add your rocks or decorations back into the tank
- Either gently pour or use the siphon to fill the tank close to the top
- Replace or rinse the existing filter if necessary
- Put the lid back on the tank, plug back in your filter, heater and lights
- Enjoy!
How often should I do a full water change on a 3.5 gallon tank?
Ideally you never have to do a full water change. You only need to do that if your tank is seriously fouled.
Like I recommend above get a test kit, every tank and setup is different.
Test frequently and change when levels are not ideal, your tank will get into regular schedule based on the setup.
But you can never tell just by looking at it, you need to test.
Hi, I just set up my first aquarium. It is 5 gallons, filtered and heated, one male betta, two mystery snails, a moss ball, and a couple of live plants. How often do you think I should change the water? The instructions I got with the tank said to change the water once a month. It seems like every website I look at suggests much more often. I was thinking about 15% every two weeks. Thanks for all your help.
There’s so many factors in how often you need to change your water:
The best way to tell is by getting a test kit, either test strips or drops.
Test your water when you get the kit, if any levels are out of balance do a 20% water change unless levels like ammonia are way too high (the death zone) – if so do a 50% water change. Then test the water in a day or two and keep doing water changes until the water is consistently good.
Then you should be able to test once a week and see where the levels are at and get into a routine of how your particular tank setup needs to be changed.
I have a black orchid male betta in a one gallon tank. I do a water change twice a week because of the one gallon. Every time I do a water change eggplant gets so excited. Starts swimming like crazy and makes bubble nests. I clean the filter pad with the tank water. Is this OK?
Glad to hear you have a filter pad on a 1 gallon tank! Really he (eggplant) should survive fine if the water is clean.
Maybe he’s a little bored and the cleaning adds some excitement to his day, that and the bubbles nest is fine!
If you are ever gone long (vacations, etc) consider a larger tank so nobody has to do a change while you are gone but it sounds like you’re doing just fine.
We have well water at our house. Is it okay to use that as replacement water in our betta’s fish tank? Or would it be better to buy a gallon of bottled drinking water like Poland Spring and use that?
Thanks.
Hey Susan – I’d say it depends on if you ever had your well water tested. Ideally if its been tested and not contaminated with anything that could seep into the ground water, as well as free of any sort of bacteria, viruses or anything else that could be in ground water then you are safe – but get it tested. If you’ve been drinking it for years then chances are its safe enough, as betta fish live in the wild live in untested/natural water.
If you are unsure or at all worried then yes go buy some gallons of spring water.
The “bad rap” that tap water gets from all of the chemicals is that at least it kills bacteria and viruses that could be living in the water. Your job with regular tap water is then to remove the chemicals which can be done with a variety products.
Do I have to keep using the water condition from the bottles to make my BETTA water safe?
If I do not change entire tank?
And, do I need to siphon the bottom if I have no gravel?
The water conditioner is for making your tap water safe for the fish tank, removing the chlorine and other additives that get added to public water. So yes unless you are using spring water you’d need to keep using water conditioner.
If there is any debris at the bottom of the tank then yes siphon the bottom, you’ll see it going up the siphon if there is any so give it a shot.
If you don’t have gravel then consider adding some, its a great place for beneficial bacteria to latch onto in your tank, just be sure to rinse it first.
how often should i test the water for ammonia? and do i do it before or after a water change?
It depends on how “aged” the tank is, a new tank with no beneficial bacteria can reach toxic levels of ammonia in a day or two.
So if its a newer tank test more frequently and write down when you tested and what the results were, that way you can better gauge how frequently you need to test.
For instance if you test every 2 days and it takes till the 4th test (8 days) before you need a change, then next time maybe test it every 4 days to see if you are still on an 8 day schedule.
You can test after a change to see how much it dropped the level of ammonia, always nice to know where you are starting from after each change.
Hey, Bob.
Great thread. I have a question.
Is there any benefit/negative to using a fish-free separate tank to cycle water for water changes in my 3 gallon Betta tank?
I have two tanks, a three gallon with a male half-moon Betta named Dwight. I had originally gotten him moss balls and then two floating low light plants. I’m unable to recall their name, but one is long and stringy like a green onion with small root clusters that have grown quickly.
The other plant looks like a green vine, and both grows roots while floating and planted. However, I noticed Dwight getting a little bit stuck in these plants in particular. He didn’t ever hurt himself but he would lodge himself in the plant and then frantically try to move out. It only happened with that type of plant.
I like the way it looks, and had a separate tank, so I moved it there.
Long story short- as I’m already treating the second tank with only a plant and have all the backup gear to heat and filter it… Can I use it as a source for safe water changes?
I’m considering a second fish at some point but we are likely to upgrade Dwight to a 10 gallon tank soon, so I’m probably going to just have him for the time being.
Thanks! Love all the advice!
Hey Kaevan,
Interesting question!
If you are using a separate tank that is cycled as your water source for tank changes that’s great!
When a tank is cycled is really things in the tank that collect the beneficial bacteria like the substrate/gravel, filters, and other objects in the tank. So those are the items are the real source of benefit as they are coated with the beneficial bacteria. The water will contain the beneficial bacteria as well, but the items in the tank that are coated are the real nursery of the bacteria.
If your main tank isn’t cycled I would either swap the fish in the cycled tank, or borrow some items from the cycled tank and place them in tank #1 to help cycle them faster.
Hope that helps and let me know how that works out!
-Bob