r/Aquariums • u/Arcangel100 • 4h ago
Bacteria keeps dying. Help/Advice
Background info I cycled the empty 23 gallon tank for a month before seeing Nitrates and added fish gradually. 10 Cherry shrimp, 13 neone tetras, one Beta and two Sword tails. I feed the fish twice a day. AMOSIJOY 172GPH Canister Filter, with a floss pad, carbon sponge, ceramic filter rings, and Bio balls.
My problem is that my bacteria seems to die every 2 weeks or so. I see my Nitrates fall to zero, then the ammonia starts to go up slowly. I was told that maybe my filter is doing too good of a job and starving the bacteria. Is that possible? I keep having to add bacteria to the tank and I am wondering if I should just add more fish to creat more waist. I think the ammonia spike caused the beta to get a touch of fin rot, I am currently treating him for it and he is doing well. Adding the Nitrate/Nitrite readings for this tank (left) and a shrimp tank (right)
TLDR: Bacteria dies off (I think it's being starved), should I add more bio load or change the filter to something else. Also, is there something that may be killing the bacteria?
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u/EphemeralAttention 4h ago
What are your KH and PH levels like? Nitrifying bacteria use carbonates as their primary carbon source, so if your KH is dropping to zero that can cause the cycle to stall. The bacteria also work best at pH levels between 7-8. They still process waste between 6-7, but if your PH drops below 6 the cycle will significantly slow down.
Edit: fixed typos
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u/falcon_311 3h ago
I didn't know nitrifying bacteria use carbonates like that. All of my tanks run at 0kh so I guess my bacteria is living on hopes and dreams lol.
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u/Azedenkae PhD in Microbiology 3h ago
The thing is once the nitrifier population is established, their consumption of ammonia/nitrite is for energy, not for growth. So they no longer really need that much carbonate once the cycle is done.
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u/griz3lda 1h ago
That was exactly my problem. It's also dangerous for the fish. I promise you this is what is keeping your cycle from catching. go to the grocery store and get arrowhead springwater and test it for KH and pH. I use this as a K H supplement for my freshwater tank after treating it to get the pH I want. I found that there was nothing else I could add that wasn't making the pH go even crazier, you are in a precarious situation here because it's very difficult to adjust your KH without adjusting your pH when you are at zero KH. Add a gradually, don't shock your fish. Once your KH is above zero, you will be able to do other stuff to it without causing disaster and can adjust the KH through normal means. Please, please heed my warning. Do not use chemical products for conventional situations, I put a single drop of pH down in my tank and it dropped my pH by four points, I was panicking. Not 0.4, four.
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u/griz3lda 1h ago
Another issue I was having was my pH being super low. Google it, that can affect the bacteria. Cupid.
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u/griz3lda 1h ago
Lol, voice to text caught me, exclaiming at my fish, whose name is Cupid. She looked like she was bottom sitting and I got nervous but she was just zoning out lol.
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u/Azedenkae PhD in Microbiology 3h ago
A lack of carbonates may only impact the cycling process specifically, and not once it is done though. This is because once established, the population of nitrifiers no longer really need to grow.
As for pH and temperature, it does depend on the specific type of nitrifiers that one happens to cultivate. Not all prefer a relatively higher pH/temperature. Some indeed prefers pH <7. There is even an archaean nitrifier that can only perform nitrification at a pH of 4-5.5.
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u/EphemeralAttention 2h ago
Interesting, and good to know. Do you know if the ammonia oxidizing bacteria are capable of utilizing NH3 as readily as NH4+?
Based on OP's stated PH reading this wouldn't be impacting their tank, but now you've got me wondering if low pH could still result in a bottleneck to the reduction of ammonia to nitrite as a result of the low PH shifting the balance of ammonia and ammonium in solution towards ammonia. I don't know enough about the metabolic pathways and catalysts involved to know if the bacteria can process ammonia directly if it's more readily available than ammonium.
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u/Azedenkae PhD in Microbiology 2h ago
pH swings can definitely cause nitrification to slow down or stop completely, although it is not in one particular direction.
This article is about a nitrite oxidizer, not ammonia oxidizer, but similar idea: https://pmc.ncbi.nlm.nih.gov/articles/PMC4784051/. Here, a freshwater nitrite oxidizer was identified that has an optimal pH 6.8. Which means that if the pH gets lower than that, nitrite oxidation by said species slows down. But if pH gets higher than that, nitrite oxidation also slows down.
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u/Arcangel100 3h ago
Interesting, I don't have a KH tester. My pH level is 7.4 and high range pH is 7.8. I will have to get a KH tester and learn about how to balance that.
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u/EphemeralAttention 2h ago
If your PH levels are between 7.4-7.8 I wouldn't consider the KH test to be a high priority. KH is the primary buffer in an aquarium, and if your pH is in that range it's pretty unlikely that your KH would be low enough to be a concern. Paired with Azedenkae's comment above (who I'm going to defer to here as I am most definitely not a microbiologist 😅), the KH probably isn't the issue.
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u/PBJ_for_every_meal 4h ago
Amazing tank
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u/Arcangel100 3h ago
Thank you! I got lucky and found a really nice piece of wood that is the length of the fish tank with minimum cutting.
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u/falcon_311 4h ago
Excessive filtration isn't a thing, bacteria dont crash because fish don't produce enough waste as they populate to the availability. Its a normal ebb and flow of nitrifying bacteria populations. This only leaves you with something it sounds like you are already suspecting. You are doing something that is killing the bacteria and you just don't know it. It could be using an aerosol in the room for cleaning, putting your hands in with antibacterial soaps still on, etc. You just have to find what it is.
What is the water change schedule like? Is it a new problem or has it happened since the begining?
Also 0 nitrates is not a bad thing at all. It only means the plants uptaking the nitrogen faster than it's being replaced. This stuff is not food for bacteria anyway, it's the ammonia and nitrites that are. After that, the nitrates become useless for the bacteria as it is far too oxidized and is of value only to vegetation.
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u/Arcangel100 4h ago
I top off the tank daily and water change about 10% every week. The canister filter gets cleaned every three weeks or when I notice shrimp have disappeared (they like to jump in from the skimmer but they are always unharmed). Hmm maybe I am killing the bacteria somehow. I try to not rinse off the ceramic or bio balls. I just set them aside while I wipe the canister and change the floss pad. The only reason I am asking is because my Betta got a touch of fin rot and I correlated it to a spike in ammonia of .20ish.
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u/falcon_311 4h ago
Ro top off or with treated tap?
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u/Arcangel100 3h ago edited 3h ago
Yup, I use Top Fin water conditioner for every water change.
Edit: it's tap treated water in NY city.
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u/Sea_Cat_3644 3h ago
Are you using prime when you add water?
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u/Similar_Blackberry29 2h ago
i use prime when i add water and have the same issue, is that what’s killing the bacteria in mine? i have a 55 that’s been fully cycled, tons of plants, canister filter that’s never been changed and has totally crashed twice
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u/Sea_Cat_3644 2h ago
Not sure. Maybe your testing kit is off/expired? Try taking water samples to a pet store if that’s an option to find out more
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u/Similar_Blackberry29 1h ago
no they’re new test kits and the fish start looking bad, luckily we have several other tanks to move them to but i hate not being able to trust a tank and i don’t know what’s causing it. not overstocked and doesn’t happen to other tanks
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u/Azedenkae PhD in Microbiology 1h ago
No, Prime does not kill bacteria.
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u/Sea_Cat_3644 42m ago
I was more thinking the tapwater may have chlorinates. And was wondering if prime was used to counter them
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u/GarbageRoutine9698 2h ago
I have no idea why your bacteria are dying off, but I have to ask what tank that is...
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u/Arcangel100 58m ago
It's a "lifegard aquatics 22 gallon" I think it's 35.8 inches long and 11.8 × 11.8. I wanted an Ultum Nature but this one fits better next to my couch, and it was slightly better for my wallet.
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u/Substantial-Sea-3672 2h ago
What bacteria are you adding? There are nitrifying bacteria that aren’t the same type that can establish in a tank effectively.
It sounds like you’re putting in bacteria that eliminates ammonia and nitrites, preventing classic aquarium nitrifying bacteria from establishing. Then when the store bought bacteria dies you’re back to square one.
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u/Arcangel100 1h ago
I bought a used sponge filter from a local pet store to cycle the tank. For now, I have been taking one of the sponge filters from the shrimp tank to help circle the large tank when the ammonia starts to rise.
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u/Azedenkae PhD in Microbiology 4h ago
No, that is not possible for nitrifiers to die like that. They are very resilient. Even if they are starved of ammonia, they go for weeks to months before going dormant, let alone die off. That’s firstly. Secondly, even if they do die, in an established tank, it is negligible when it comes to ammonia produced from their reduction in population.
So now, questions. You are not replacing filter media, right? What bacteria product are you adding? Has the pH been consistent? How high does ammonia actually get?