fishless cycle - unexpected spike

[sif]

OK, thought I'd completed a textbook fishless cycle... no nitrites for 4 days, nitrates through the roof at over 100ppm. Do a 70-80% water change in anticipation of first stock going in tonight used aquasafe which I thought was OK. This morning I'm showing a healthy 15ppm nitrates BUT 0.5ppm nitrites. What have I done wrong? I did put in my usual drops of ammonia last night to keep the bacteria colony fed but I'm very surprised to see this nitrite level!!

Simon

 

[newland]

Sounds like a mini spike. probably due to the large water change and the 0 nitrites fr 4 days. Keep running the fishless cycle for a little while until its all 0 and everything should be good.

 

[One_Trick_Pony]

yeah maybe wait a couple more dyas

 

[sif]

So is it usual to see a nitrite reading after say a weekly water change on a mature tank?

 

[CFC]

No, but yours is not a mature tank. It takes several months for a tank to become completely stable and until then such large water changes will affect the balance of things. Leave the tank for another day or so for the nitrite to go down again and then add some fish after a smaller 20% water change.

 

[rdd1952]

If you added ammonia last night to keep the bacteria fed, it would be normal to see some nitrite this morning. The ammonia woulld have been transformed to nitrite overnight. The nitrite should be gone by evening.