Cycling a tank

I have a 125 litre tank which ive had for about 3 weeks. The last 4 days or so the Ammonia and Nitrite have been at 0.5ppm and the nitrate between 10-20ppm. I've been doing daily water changes(about 20%) since but the levels dont seem to be going down. Do i need to do a larger water change or is this normal and it should soon go down?

It was my understanding the ammonia gets turned into nitrites which then get turned into nitrates so if I have nitrates present shouldnt the nitrite be going down and in turn the ammonia going down also?

Cheers,

The cycle is not always as straight forward as it seems. You are correct that 'ammonia gets turned into nitrites which then get turned into nitrates'.

You may just need to be patient until the ammonia and nitrite continue to convert into nitrAte.

I would not continue to do the water changes as this will affect the amount of ammonia and nitrite that is in the tank and you want this to be available to be fed on by your beneficial bacteria.

Water changes are only needed once the nitrAtes begin to rise to around 40ppm, since there is no more conversion once the nitrAtes appear and they are toxic above 40ppm.

Ideally, you want to continue dosing your tank with ammonia slowly to bring the levels up in increments, this will keep feeding your bacteria, creating a strong cycle.

Are you cycling with an Axolotl in the tank? If you are, you should transfer it to a large plastic container with daily water changes and finish your cycle with a different source of ammonia. This way your Axolotl does not get stressed or harmed since the high levels of ammonia and nitrite are toxic

Caudata Culture Articles - Water Quality
Caudata Culture Articles - Cycling

Just to be clear, If you are keeping the axolotl in the tank instead of removing it, you do need to keep up the water changes to keep the ammonia and nitrite low enough to not harm your axolotl. The ammonia limit depends on pH and water conditioner used. The nitrite limit recommended by experienced keepers is 0.25 ppm, although modern conditioners claim to neutralize that for a while.

You can cycle faster by removing your Axolotl, then you can have higher levels of ammonia and nitrite. This also removes any chance of stressing your Axolotl