My cycle has seemingly disappeared months later.. help?!

JamesRush93

Member
I set up my first 5 gallon planted tank on Nov 9, 2020 and it had been successfully cycled by Dec 1, 2020. I unfortunately had to do a fish-in-cycle with a betta fish and I used Seachem Stability to help speed up the process but everything worked out fine. After the cycle was complete the plants have grown in healthily and it's been looking great with a steady 5-10 ppm reading of nitrates and 0 ppm for ammonia and nitrites. However, about two weeks ago I did a water test and there were no longer any nitrates. My plants include small java ferns, java moss, a marimo moss ball, an anubias nana, hornwort and frogbit. The frogbit and the anubias nana were the last plants I added before my nitrates disappeared. The frogbit has been growing long roots like crazy and multiplying rapidly since I put it in and even the anubias which is supposed to be slow growing grew a full large leaf in about 2 weeks.

I've done enough research to know that a heavily planted tank (like mine) can deplete all your nitrates as your plants consume them to grow. However, what's confusing and concerning to me is that I am now getting ammonia reads of up to .50 ppm which I haven't seen since I started my cycle months ago! Shouldn't a fully cycled tank have bacteria established that should convert any ammonia to nitrates? Also, to add to the confusion, since losing all my nitrates the pH has gone up and stabilized itself at 7.8. I had it at a neutral 7 for the betta up until then.

I'll admit I'm new to the hobby but I've done my reasearch and know I did the cycle correctly. Everything went perfectly until now months later I have no more nitrates, I'm getting ammonia reads that constitute water changes and to top it all off my pH has decided to shoot up and doesn't seem to be coming back down. The fact that I'm even seeing ammonia at this point without any nitrates suggests to me that my cycle has disappeared and decided to start over? Can this happen if your tank is too heavily planted? Any advice or insight would be much appreciated!
 

StarGirl

Member
Have you checked your tap water? They change stuff on you once in awhile.
 

Dunk2

Member

Cherryshrimp420

Member
Seems like your buffer (KH) got used up....pH swings can affect BB and start a mini-cycle.

So what did you mean by "had it at a neutral 7"? Did you do anything to the water to change its pH?
 

John58ford

Member
Plants love low kH, the lower it gets the faster they use up the nutrients. Bacteria need that kh. So when depleted the cycle will stall. Ammonia is less toxic in low ph so it's not usually an issue/solved by water changing but... I don't know how your pH would shoot up and stay up with low kH though so it's a head scratcher.

What testing kits are you using?

Can you let a glass of tap water sit out over night, then test that, and the tank, with every kit you have and post both sets of the results?
 

Cherryshrimp420

Member
John58ford said:
Plants love low kH, the lower it gets the faster they use up the nutrients. Bacteria need that kh. So when depleted the cycle will stall. Ammonia is less toxic in low ph so it's not usually an issue/solved by water changing but... I don't know how your pH would shoot up and stay up with low kH though so it's a head scratcher.

What testing kits are you using?

Can you let a glass of tap water sit out over night, then test that, and the tank, with every kit you have and post both sets of the results?
Toronto tap water (which is what I'm using) has pH 7.8 so that part seems the most normal to me. I'm more curious how he got his water to pH 7. Maybe added some acid that ate up all the buffers and then a water change brought the pH back up ?
 
  • Thread Starter

JamesRush93

Member
Sorry for the late reply I appreciate all your input!

Dunk2 said:
Have you cleaned your tank or filter or removed anything from the tank (substrate, decorations)?

You've used water conditioner (dechlorinator) for each water change?
I should clarify I use a sponge filter and haven’t done anything to it other than take it out once after it was cycled to squeeze it’s water into a cup to use for a different aquarium. Haven’t removed anything else either. Definitely been using water conditioner every time I add water, I use Seachem Prime.


Cherryshrimp420 said:
Seems like your buffer (KH) got used up....pH swings can affect BB and start a mini-cycle.

So what did you mean by "had it at a neutral 7"? Did you do anything to the water to change its pH?
Ill be honest I’m not very familiar with KH.. I’ll look that up unless someone has a simple rundown of it or useful links I should read! I know it means your water hardness but I haven’t tested for that (nor do I know how) and I’m not sure how it fits in to the other water parameters. I didn’t add any chemicals to the water but I have two medium pieces of driftwood in the tank and Fluval soil substrate which apparently lowers the pH. I boiled the driftwood a lotbefore adding it though so there aren’t tannins in the water. Maybe there was a bit before but it’s been removed or evaporated over time?

John58ford said:
Plants love low kH, the lower it gets the faster they use up the nutrients. Bacteria need that kh. So when depleted the cycle will stall. Ammonia is less toxic in low ph so it's not usually an issue/solved by water changing but... I don't know how your pH would shoot up and stay up with low kH though so it's a head scratcher.

What testing kits are you using?

Can you let a glass of tap water sit out over night, then test that, and the tank, with every kit you have and post both sets of the results?
I’m using the API master test kit which can test for pH, high range pH, ammonia, nitrite and nitrate. What would I need to test the KH? Not very clear on what that is exactly, it’s clear I need to learn more about that! I’ve left a glass of water out over night I’ll test it tomorrow and update here.

Cherryshrimp420 said:
Toronto tap water (which is what I'm using) has pH 7.8 so that part seems the most normal to me. I'm more curious how he got his water to pH 7. Maybe added some acid that ate up all the buffers and then a water change brought the pH back up ?
I didn’t add any acid but i do have driftwood in the tank. Although i boiled out the tannins before adding it. Either way my pH in the tank for sure used to be 7-7.2. It would be higher after a water change but then if I tested it the next day it would be lower. I just thought that was normal and ideal since they say the ideal ph for a betta fish is 7.
 

Cherryshrimp420

Member
JamesRush93 said:
Sorry for the late reply I appreciate all your input!



I should clarify I use a sponge filter and haven’t done anything to it other than take it out once after it was cycled to squeeze it’s water into a cup to use for a different aquarium. Haven’t removed anything else either. Definitely been using water conditioner every time I add water, I use Seachem Prime.




Ill be honest I’m not very familiar with KH.. I’ll look that up unless someone has a simple rundown of it or useful links I should read! I know it means your water hardness but I haven’t tested for that (nor do I know how) and I’m not sure how it fits in to the other water parameters. I didn’t add any chemicals to the water but I have two medium pieces of driftwood in the tank and Fluval soil substrate which apparently lowers the pH. I boiled the driftwood a lotbefore adding it though so there aren’t tannins in the water. Maybe there was a bit before but it’s been removed or evaporated over time?



I’m using the API master test kit which can test for pH, high range pH, ammonia, nitrite and nitrate. What would I need to test the KH? Not very clear on what that is exactly, it’s clear I need to learn more about that! I’ve left a glass of water out over night I’ll test it tomorrow and update here.



I didn’t add any acid but i do have driftwood in the tank. Although i boiled out the tannins before adding it. Either way my pH in the tank for sure used to be 7-7.2. It would be higher after a water change but then if I tested it the next day it would be lower. I just thought that was normal and ideal since they say the ideal ph for a betta fish is 7.
Ah okay I see... fluval has an active substrate that will bring pH down. That might be what you are using. That substrate is usually used for organisms that like acidic water, but is not necessary for bettas.

KH is buffering capacity and is different from water hardness which is GH. Usually active substrate is used with re-mineralized RODI water. Toronto water is hard and high pH so it kind of defeats the purpose of active substrate.

I guess the one solution would be to only do water top-offs with RODI water and water changes with re-mineralized RODI water. The more annoying solution would be to change out the substrate to an inert substrate.
 
  • Thread Starter

JamesRush93

Member
John58ford said:
Plants love low kH, the lower it gets the faster they use up the nutrients. Bacteria need that kh. So when depleted the cycle will stall. Ammonia is less toxic in low ph so it's not usually an issue/solved by water changing but... I don't know how your pH would shoot up and stay up with low kH though so it's a head scratcher.

What testing kits are you using?

Can you let a glass of tap water sit out over night, then test that, and the tank, with every kit you have and post both sets of the results?
So my tap water after letting it sit a day reads 7.8 and I'd say my tank looks closer to 7.4 after checking it again. The colour from the test looks slightly more yellow than orange. I really was used to my pH being closer to 7 but it would always be higher immediately after a water change. It wasn't until the next day that I'd test it and find it back to around 7. Might have been due to the fluval shrimp soil and the driftwood?
 

Cherryshrimp420

Member
JamesRush93 said:
So my tap water after letting it sit a day reads 7.8 and I'd say my tank looks closer to 7.4 after checking it again. The colour from the test looks slightly more yellow than orange. I really was used to my pH being closer to 7 but it would always be higher immediately after a water change. It wasn't until the next day that I'd test it and find it back to around 7. Might have been due to the fluval shrimp soil and the driftwood?
Yes that is exactly what active substrate does
 

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