7Th Week Of Fishless Cycle

[`Peter]

So my ammonia has finally been able to drop to 0 in 12 hours from 3ppm. Problem is now my nitrites are sky high again at about 5ppm which I did not expect. My nitrates are at 30ppm which is expected towards the end of the cycle before I do my 90% water change.

What could be the cause of the nitrite spike?

Thanks

 

[TrainRek77]

Seems like a crazy long time for an aquarium to cycle? The only reason both ammonia or nitrite spike is from the lack of a biological filter. I don't know the ratio but 1 ppm of ammonia makes much more than 1 part of nitrite. I know none of this information really helps, but 7 weeks to cycle? Are you planning on filling the tank to full capacity after you are done?

 

[Xraymark]

If this is the first nitrite spike then it will go above 5. Only redose ammonia 1-2ppm until your nitrite zeros. Consider a 50%water change to bring the nitrites down to readable measurement. If too high it can promote the wrong bacteria growing.
This would be seen as stage 2 in the cycle. Nitrates at 30ppm is not high. At the end of the cycle it will probably be well above 100ppm.
Is this the first nitrite spike?

 

[Ram8349]

It seems you have had enough bacteria to feed on ammonia, yet not enough bacteria to feed on the nitrite converted from the ammonia.

There is nothing to worry about. It is normal to take 6~8 weeks to completely cycle a new fish tank.

However, there are certain tips to speed up the fishless nitrogen cycle you might want to try out if it is not yet completed.