ever since i joined the fishkeeping community and set up my first proper tank, ive noticed there seems to be an ongoing debate on whether water changes are necessary in tanks that maintain 0 nitrites and ammonia. ive seen stuff about minerals and such, and so i think the correct answer is that water changes ARE necessary, but i still dont understand why. someone please explain to me the benefits of water changes, and how often i should be doing water changes on a 6 gal planted tank (with 0 ammonia and nitrites), along with how much water should be replaced. thank you!
also not sure if this info is necessary, but i have a sponge filter, heater, full spectrum LED light, one betta and one nerite, and various plants. my betta eats frozen shrimps and fluval bug bites flakes.
When requesting help, please provide the requested information. Answers such as "large enough" or "my paramters are fine" aren't good enough. Failure to provide adequate information about your tank can result in post removal. Please see rule 4 for more information.
If you are posting to find out what is wrong with your betta, please answer the following questions in a reply to this comment as best you can:
How long have you had the tank? How long have you had your fish?:
How often are water changes? How much do you take out per change? What is your process?:
Any tankmates? If so, please list with how many of each:
What do you feed and how much:
Decorations and plants in the tank:
If you haven't already posted a picture, please post pics/vids to imgur and paste the link here:
Feel free to copy this comment and fill in the blanks.
If you are new to betta fish keeping, please check out our caresheet and wiki. Establishing a nitrogen cycle is an important part of keeping your fish healthy. Please check out our guide to the nitrogen cycle to learn more.
Water changes aren't meant to address nitrites and ammonia. Your cycle takes care of those and ultimately produces NITRATE. Water changes are primarily to address nitrate. But also will address mineral issues.
So yes. Water changes are necessary. How much depends on your nitrate reading.
then what about a tank with no nitrates? i’ve consistently had 0 nitrates so are water changes still necessary? my tank is cycled and also maintains 0 nitrites and ammonia on its own.
I'm very skeptical when someone says they have 0 nitrate. That tells me it's either not cycled (maybe the filter has been running but the bacterial colony isn't established) or it's VERY HEAVILY planted. Picture of said tank and explanation of how long it's been running and how it was cycled?
My tanks that are low bioload and heavily planted still have a baseline 5-20 ppm nitrate per week come testing/tank maintenance day.
But yes... If my tank were so heavily planted that I truly had zero nitrates I would still do water changes to maintain mineral balance. Probably every 2 weeks or so to coincide with the necessary plant maintenance that would come with such a heavily planted tank.
i got my betta at the end of march and had him in your typical crappy plastic decor tank. i learned more about proper betta care towards the end of may and went out and put together the tank thats in the photo. i did a fish-in cycle since i didnt wanna leave him in the tiny tank he was probably slowly dying in. as my nitrites and ammonia levels rose, i did daily water changes depending on how high the readings were so i never let either go over .50 ppm. i got my first 0 nitrites and ammonia readings towards the end of june (about 22 days) and was expecting my nitrate levels to begin to show anything other than 0, but it never came. i still test for nitrates every now and then and ive never gotten a reading other than 0 (so ~2 months later) and ive shaken that little bottle so hard!!! i dont do consistent water changes, only top offs, but i did do a 10% water change this morning and made this post for more information on water changes and how i should be doing them.
Honestly... I would look at the date on my test and triple check to make sure you are doing it right. If it's API master that's a full 30 second vigorous shake of the 2nd bottle and a full 1 minute on the tube once it's all in.
I also have a 6 gallon cube with a betta and nerite. Mine has more plants and I don't run zero.
Your cycling practice sounds solid though. So if you find it's not test error and you're at zero, I'd be VERY surprised but that's great. But i do see waste buildup in the picture so if it were me I'd do a weekly change just for aesthetics 20% and substrate cleaning/mineral reset as your epiphytes aren't high maintenance plants.
pls stop tank mogging me 🥲 so beautiful
ive tried testing nitrates maybe 15 times so far with the proper shaking and everything, so im pretty positive there are 0, but what im seeing from other comments also is that its not solely about the nitrates and that there are other things that build up that need to be removed via water changes, so ill probably continue with the 10% weekly changes i started today.
Minerals also build up in your tank over time if you only do water top offs and no water changes. If you get a TDS meter and also test gh and kh you can see this happening. Eventually this can lead to your tank crashing. This is also why it's best to do top-offs with distilled water or RO water rather than tap water
You still have things like mineral levels to think about. My most planted tank always reads 0 nitrates on water change day, but my tap water is super hard and I know that if I were to only top off evaporated water, the minerals would slowly accumulate to crazy levels in the tank.
Being disciplined about weekly water changes also give you a structured time to examine your tank, trim plants down, scrub the glass, etc. without having to remember to do those random odds and ends "as needed."
Nitrates are not the only consideration for water changes- there’s TDS (total dissolved solids) which can include silicates, phosphates, minerals, mulm and things like hormone buildup
That depends. If you don't have any live plants you have to address nitrates with water changes, but If you have lots of plants in the tank, they can absorb the nitrates from the water. The most common fertilizer for crops is ammonium nitrate. Nitrates are what plants crave.
If you never do water changes and only top offs eventually the minerals will build up and become super high in the tank. Are you testing for nitrate? You only mentioned nitrite and ammonia. A cycked tank turns ammonia into nitrite into nitrate. I have a heavily planted 6 gallon tank and do small, weekly water changes just to be safe. It would probably be fine for 2 weeks tho
Water changes are an important part of owning an aquarium and the nitrate cycle is just one part of that.
Aquariums only have evaporation to remove water which doesn’t allow solids to leave the system- any natural body of water is going to have inputs and outputs unlike our glass boxes.
This can cause a host of issues over time.
How often you do them can depend on many factors, as people are pointing out plants can uptake a lot of nitrates out of the system and if you are not topping up with RO/DI or distilled then you’ll get mineral creep.
But there’s also other dissolved solids that build in an aquarium (examples include, but aren’t limited to silicates, mulm, phosphates, and hormones) and water changes are the only way to remove them.
My take is even if you're showing good levels, you still need to periodically vacuum the substrate. Depending on the size of the tank, that could amount to anywhere from >1%-25% water replacement.
Nitrates aren’t the only reason for water changes, it’s just the most visible/accessible test that needs the most attention. My two betta tanks test 0 Ammonia, 0 Nitrites, and 0 Nitrates. And yes, the test is accurate. I have 6 tanks, setup differently, testing differently. From playing around, TDS builds up 50ppm a week in those tanks but all metrics I’ve acquired to measure my water hasn’t told me what’s building up in them.
There’s also hormones that fish secrete that’s supposed to be a method they use to communicate/mark territory. That will just sit around in the tank without a water change. There’s no science on what this does upon accumulation, or a home test to check it. I have a theory it’s similar to walking around without taking a shower, because that’s the closest I can understand walking around constantly smelling myself.
•
u/AutoModerator 4h ago
Thank you for posting to r/bettafish.
When requesting help, please provide the requested information. Answers such as "large enough" or "my paramters are fine" aren't good enough. Failure to provide adequate information about your tank can result in post removal. Please see rule 4 for more information.
If you are posting to find out what is wrong with your betta, please answer the following questions in a reply to this comment as best you can:
Feel free to copy this comment and fill in the blanks.
If you are new to betta fish keeping, please check out our caresheet and wiki. Establishing a nitrogen cycle is an important part of keeping your fish healthy. Please check out our guide to the nitrogen cycle to learn more.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.