Nitrites spike in apparently cycled tank

[Abyssal Pyre]

Hi everyone,
I have a problem with nitrites in my tank. It's been 40 days of cycling now, and I thought it was ok.
I started cycling with a canister filter, using the "sera bio nitrivec" liquid bacteria to establish the nitrogen cycle, I put the bacteria every time I do a water change depending on how much water I change.

I had a lot of ammonia the first weeks, and it spiked up and down a bit. Nitrites started appearing soon after, and they spiked to 1.7 mg/l (ppm) more than two weeks ago. I did water changes weekly, doing a bigger 75% water change when nitrites spiked. This week, ammonia and nitrites were stable for a few days, and nitrates appeared. The readings were constant, water tested every day:
0.004 ppm NH3
0.000 ppm N02
10 to 20 ppm N03 (varying)
So yesterday evening I decided to put the little axie in, who was super happy to be in his new tank.

This morning though I tested my water, and the values were:

0.004 ppm Ammonia
0.5 (maybe MORE) ppm Nitrites
0.25 ppm Nitrates

Ph has always been a stable 7.5, temperature 17-19 degrees
I quickly tubbed the little guy out of the tank in fresh dechlorinated water (as he was before). I re-tested to make sure it wasn't a false reading, and it was not. I also tested my tap water to make sure it was ok, and it has 0 Nitrites.

My question is: WHAT THE HELL IS GOING ON IN MY TANK? Lol
I assume cycled hasn't kicked in yet, but what should I do next? Why this cycling is so weird and going up and down in values compared to the "linear" cycling phases I see online?

 

[HermitMandy]

Hello! What's likely going on is that the nitrifying bacteria that were taking care of the previous ammonia load cannot fully keep up with the ammonia load the axolotl is producing. So your nitrogen cycle is there and technically completed,but just needs some help and a little extra time to keep up.
While I'm not personally experienced using the Sera bio nitrivec (we sell aquavitros seed at my work instead), any kind of nitrifying bacteria will need an ammonia source. I'd personally kick up the ammonia levels and give it more time to settle out/work itself out while adding more of the bottled bacteria.
And don't worry, its not just you that cycling isn't linear for! Ive experienced both sides of it with my own tanks-some cycle without showing any major spike (nitrates just start showing up), and others has been ammonia city for weeks before settling out.

 

[GulfCoastAxolotls]

Hi everyone,
I have a problem with nitrites in my tank. It's been 40 days of cycling now, and I thought it was ok.
I started cycling with a canister filter, using the "sera bio nitrivec" liquid bacteria to establish the nitrogen cycle, I put the bacteria every time I do a water change depending on how much water I change.

I had a lot of ammonia the first weeks, and it spiked up and down a bit. Nitrites started appearing soon after, and they spiked to 1.7 mg/l (ppm) more than two weeks ago. I did water changes weekly, doing a bigger 75% water change when nitrites spiked. This week, ammonia and nitrites were stable for a few days, and nitrates appeared. The readings were constant, water tested every day:
0.004 ppm NH3
0.000 ppm N02
10 to 20 ppm N03 (varying)
So yesterday evening I decided to put the little axie in, who was super happy to be in his new tank.

This morning though I tested my water, and the values were:

0.004 ppm Ammonia
0.5 (maybe MORE) ppm Nitrites
0.25 ppm Nitrates

Ph has always been a stable 7.5, temperature 17-19 degrees
I quickly tubbed the little guy out of the tank in fresh dechlorinated water (as he was before). I re-tested to make sure it wasn't a false reading, and it was not. I also tested my tap water to make sure it was ok, and it has 0 Nitrites.

My question is: WHAT THE HELL IS GOING ON IN MY TANK? Lol
I assume cycled hasn't kicked in yet, but what should I do next? Why this cycling is so weird and going up and down in values compared to the "linear" cycling phases I see online?

You can have a fully cycled tank and still have chemical fluctuations when adding livestock. Your tank just needs time to compensate for the ammonia your axolotl is producing. It's a completely normal occurrence. No need to panic. Do a small water change and add a bit more bacteria. It'll level out fairly quickly.