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 8h 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 7h 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 7h 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/falcon_311 7h ago

Oh, that's cool

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u/griz3lda 5h 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 5h 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 4h 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/TofuttiKlein-ein-ein 4h ago

Cute name!

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u/Sea_Cat_3644 4h ago

Wow with 1 drop!!