Fishless Cycling Help

[PaulM]

Good evening all,
I recently purchased a 120l tank and am currently doing a Freshwater fishless cycle with Dr Tim’s Ammonia. I had tried with household ammonia in the beginning but didn’t seem to be getting anywhere. About two and a half weeks ago I did 100% water change and added Dr Tim’s One and only and Ammonia. I am now at the stage where 2ppm or Ammonia is processed in to Nitrite in less than 24hrs. My issue is with Nitrite and Nitrates. Two days ago I realised that my Nitrites were off the chart and read that this could stall the cycle. I decided to do a 90% water change and this brought my nitrites and nitrates right down to a readable level. I then decided to dose the tank back up to 2ppm Ammonia and this has been processed to Nitrite in less than 24hrs. When I tested Nitrites tonight they are 5ppm+ and Nitrates are around 80ppm. Ammonia was zero. Ammonia is obviously being processed fine. Nitrite must be being processed as there are Nitrates but could it be that there is not enough bacteria yet to process all the Nitrite? I did also read the presence of a lot of Nitrites in a test will also give a positive nitrate test even if there isn’t any? Any suggestions on what to do?

[Aiken Drum]

Your assumption that there is insufficient bacteria to process all the nitrite to nitrate is correct.

The nitrite to nitrate stage always seems to take longer than the ammonia to nitrite stage.

Your method of doing a water change to keep your nitrite within readable range is the right way to go. Ive heard that high nitrite stalls a cycle, other people says it doesnt. But, i always like to keep levels readable regardless.

For info. 1ppm ammonia cycles out to 2.7ppm nitrite and then 3.6ppm nitrate. So your 2ppm ammonia will quickly take you above readable nitrite if it isnt all being converted nitrate.

Keep going, you will get there. You are doing the right things.

[PaulM]

Hi Aiken Drum,

Many thanks for your reply. It really is appreciated. I think I’ll do another partial water change to bring the nitrites back down to readable figures. Shall I continue to feed ammonia at 1ppm?

[Aiken Drum]

When i start to see ammonia being consumed in 24h and nitrite going off the charts i do a water change to bring them to readable levels then dose the ammonia up to 1ppm. This means your nitrites are being kept lower. You can then up the ammonia dosing back up to 2ppm when the 1ppm is being fully processed out in the knowledge that some nitrite is being processed.

Whether you want your cycle to be processing 1ppm or 2ppm ammonia or more depends on your stocking plans. If you plan on a light stocking to start with, then processing 1ppm per day is fine. If you plan on a more moderate stocking straight away, then you probably want to up this 2ppm. I always start with a light stocking, so just wait for 1ppm to process out. In reality, a normally stocked tank wont produce close to 1ppm ammonia per day.

Originally Posted by PaulM

Hi Aiken Drum,

Many thanks for your reply. It really is appreciated. I think I’ll do another partial water change to bring the nitrites back down to readable figures. Shall I continue to feed ammonia at 1ppm?

[PaulM]

That’s great thanks. Water change is done so I’ll test later to check the nitrites have come down before dosing 1ppm ammonia.

[PaulM]

Just an update. My tank started processing 1ppm ammonia right through in just over 24hrs on Thursday and then less than 24hrs by Friday. Did a small water change to lower nitrates and have now got a couple of guppies and a few neon tetras in the tank. Thanks again for all your advice. I will be stocking slowly and guess that I just need to watch the bioload adjusts accordingly.