Where Have My Nitrites Gone?

The theory is that as ammonia goes down, nitrite goes up; then nitrite goes down and nitrate goes up. But in practise things often behave differently.


Can I just check with you:
You added a dose of ammonia on day 1 - how much ammonia did you add?
This dropped on day 13 so you added a second dose - how much ammonia did you add the second time?
Since then you have has constant 4ppm ammonia and 5ppm nitrite until today - have you added any more ammonia apart from day 1 and day 13?
Today (day 31) the ammonia reading was the same and the nitrite reading had dropped
Nitrate readings were higher on day 13 than on day 31.


The fact that the nitrite reading has suddenly dropped suggests that you have just grown a lot of nitrite eating bacteria. It is common to hear of cycles where the nitrite level stays constant then drops to almost zero overnight. If there was no nitrite being made it would stay constant until the bacteria grew, then suddenly drop.
The fact that the nitrite level stayed constant and that the ammonia level also stayed constant suggests that something has happened to your ammonia eaters. Once the ammonia level drops, with an accompanying rise in nitrite, further additions of ammonia should drop quickly and the nitrite level should go up further until the nitrite eaters grow.


So what has happened to your ammonia eaters? Have you done anything at all to the tank, added anything other than ammonia? Did you add more ammonia that you should have done on day 13? If you added the correct amount of ammonia and done nothing else to the tank, I'm at a loss 

I think what I'd do in this situation would be a very large water change. Then test the ammonia level half an hour after you've filled up. If you have a reading, subtract that from 3ppm and add enough ammonia to make the reading up to 3ppm - do another test half an hour after adding the ammonia to confirm you have added the right amount. I know the API tester doesn't have a colour for 3ppm so aim for more green that 2ppm but less than 4ppm.
When have you been doing the tests? I know that the light under which you compare the colour of the tube to the chart can have an effect and give a false reading. I did an experiment with all the different bulbs in our house. Daylight is the best light source, though you need to be at home during the day for that. Old fashioned light bulbs and halogen light bulbs give the same reading as daylight. But fluorescent and compact fluorescent (energy saving) bulbs/tubes give a different reading from daylight. We didn't have any LED bulbs when I did the experiment so I don't know about those. If you read the tests under fluorescent light, it is possible you got a false reading for ammonia - and a too-high ammonia level causes the cycle to stall.

Your tank is the same size as my Rio. A 100% water change will take ages, I'd try about 50%. That's quite a bit but not nearly such hard work.

The bacteria grow faster towards 30 deg, but they will grow, albeit a bit slower, at 27.


If your ammonia is 9.5%, and removing a bit of water volume for substrate and decor if you have them in leaves about 105 litres (using my tank as a guide  ). That needs 3.32ml ammonia to get 3ppm.

There is one thing you could try which might work - but it's not guaranteed - get a bottle of Tetra Safe Start.

Your water company may be very good at killing bacteria so that you have very very few in your water supply. The chap who wrote the new method of cycling has actually commented on the 'other forum' that UK residents seem to take much longer to cycle than in the USA, and he too puts it down to lack of natural bacteria. Adding Safe Start might not do anything or it might help. It won't do any harm. And I mean Tetra Safe Start, no other product. Apart from Dr Tim's One and Only (which you have to buy on-line and may or may not survive the import process) all the others contain the wrong species of nitrite eating bacteria