Has my cycle crashed?

I recently moved house and drained the tank by over 3/4 to move it. The tank still has all its original ornaments and substrate, and I've not changed the filter media, but I did clean some algae off the glass after I emptied it.

Previously, the tank had 0 ammonia and 0 nitrite, with nitrates at around 40. Today, I noticed the ammonia and nitrites were at 0.25, and the nitrate at 20. Have I crashed the cycle by changing so much water and cleaning the glass? Will I have to start all over again?

It is not uncommon to start a mini-cycle when doing a very large water change.
I've read about it several times on a fish forum, and it is common when people move tanks or are a bit over enthusiastic when cleaning a filter.
You wouldn't normally have to start again, just monitor the water daily and do regular (daily or every other day) smaller water changes to keep to levels of toxins down whilst the cycle re-establishes.
If you have any concerns then you can always put your axolotl in a smaller tank/container and do daily 100% water changes (with dechlorinated water) on the small tank, whilst using bottled ammonia to complete the cycle in your larger tank.
I'm fairly new to this, so some of the more experienced keepers may have more advice for you.
Best of luck with getting your tank sorted. :happy:

thanks for the advice - I hope that's all it is! I'll be keeping an eye on the levels daily to make sure it doesn't get out of control. I just hope it's not going to need full re-cycling!

回复: Re: Has my cycle crashed?

So I tested the water again today and the ammonia showed as 0.25, the nitrite at 0 and nitrate at 20. I tested the tap water and it came up as 0.5!! From a different tap it seemed to test clear so I did a partial water change using that instead. Not sure at all what's going on with my cycle here - it all seemed ok for the last couple of weeks

Be careful as, when doing some research to answer another thread recently, I found that if your water company treats with chloramine instead of chlorine this can cause a positive ammonia test result. You need to make sure that your water conditioner/dechlorinator treats for chloramine as well, and make sure you treat your water because leaving it stand to get rid of chlorine does nothing for chloramine.
Don't panic yet, but do check your water conditioner is suitable.

You're okay. Just keep monitoring as you are doing - the ammonia is not at a dangerous level and is dropping. It should continue to do so until it is back to zero. The nitrites and nitrates readings are fine.

Donna - that's really interesting! I use API water conditioner which does remove chloramine as well, so that's a relief. The lotls seem perfectly fine right now so I'm going to keep an eye on the ammonia levels and hopefully it'll be fine. Thanks both for your advice