cycle question

[mark shirah]

what would cause nitrites to go to 0 before ammonia goes to 0 ? i used ammonia to start cycle. every thing went as expected. after after 4 weeks nitrites spiked then nitrites went to 0 but ammonia stayed at about 1-2. if i dose with ammonia it does not go away within a 24 hour period. am i cycled ?

 

[Bubble_B0y]

before we start - do you have nitrates????
if no, then you must wait before the ammonia reaches zero.
if yes and nitrates are detected, then your tank is cycled

To answer your question......
In an Un-cycled/Non-cycled tank, it is unusual for nitrites to go to 0 before ammonia
BUT, in a fully cycled tank - it is extremely common !!

The main reason for detecting ammonia in a fully cycled tank and having zero nitrite, is because the tank has reached the limit/saturation for ammonia and cannot support the "ammonia" bioload.

Remember:
the good bacteria for ammonia and nitrite are DIFFERENT, and have different requirements.
The nitrite level is NOT an indication of the ammonia level (this is why both MUST be tested)
Hence, its possible to have zero nitrite, and have detectable amounts of ammonia in a fully cycled tank


To fix this.....
I would try increasing aeration to maximum - add lots of airstones to increase the oxygen (good bacteria needs oxygen to grow - especially the good bacteria for removing ammonia)
If this is a fishless cycle, I would stop adding ammonia and wait to see if the level decreases with the extra oxygen.

good luck

 

[Fishyfanatic]

Does your local water company use chlroramines instead of chlorine? What kind of dechlorinator are you using?

 

[TankGirl]

If you dose ammonia and it does not go away in 24 hours you are not cycled. I would ignore other test readings and simply wait for ammonia to zero out, then concentrate on nitrite readings.

 

[Guest]

I agree with TG completely. Though the other readings may indicate that the tank may already be fully/partially cycled, I would wait for the ammonia readings to go to 0, then look towards the nitrite readings.

 

[TomK2]

I would consider cutting back on the ammonia source. I bet a dose that produces 0.5ppm would feed and grow your ammonia bacteria and your nitrite bacteria. When that level goes to zero for both ammonia and nitrite you will be done. I presume your nitrite spike lasted several days if not a week or so? Just checking to make sure it wasn't a one day thing, since that would probably be erroneous. Also, as suggested, you need to see the confirmatory rise in nitrates. And as stated, if you are doing water changes with dechlorinated chloramine water, that adds to the ammonia load. Dont forget that the bacteria are sensitive ot pH, and nitrification stops at a pH of 6.