fishless cycling - screwy levels

[tedek]

I have been doing a fishless cycle of my new tank for about 3 weeks and everything has been moving along nicely...until today.
After seeing ammonia dropping (and dosing it back up), nitrites high, and nitrates steadily increasing for a week or so, I tested the water tonight and got rather unexpected results.
Ammonia is at 2ppm, nitrate is about 20ppm, but nitrite is 0ppm! If ammonia had been 0 too I would have thought the cycle was complete, but it's not so I am really confused.
Why would nitrite have disappeared but not ammonia?
PH is on the low side (6.4 or so) but it was even lower the other day and I did a PWC to bring it up.
Should I do another PWC? Could I be getting a false ammonia reading?

 

[tedek]

As an additional comment, when I did the PWC the other day I used api stress coat plus to treat the tap water. Could that have neutralized the nitrite?

 

[trennamw]

I'm by no means an expert here - I'm heading toward the end of my first fish less cycle too ...

But you said you are re-dosing with ammonia?

I wonder if it's that your initial ammonia is totally processed and a subsequent dose is just starting to process. So you'll see a drop in ammonia and a rise in nitrite soon.

Ammonia A is all gone --> Nitrites A are all gone --> Nitrates A is 40
Ammonia B is 2 --> No Nitrite B yet --> No Nitrates B yet


Aaaaaannnd ... I just restarted my cycle with plain dechlorinator after a month's cycle didn't go much of anywhere with Stress Coat in it.

My assumption was Stress Coat neutralizes nitrites by putting in the bacteria that convert it to nitrate, but maybe not. And maybe the "coat" stuff isn't helpful for bacteria populations. Doesn't kill them just slows things down?

But that's a big assumption. I also restarted with a huge amount of donated filter media that was very, very, very populated with bacteria. Could be even with the stress coat it would have been fine.

Question would be whether salicylates (which are in aloe) slow down the bacteria life cycle at all.

 

[tedek]

I have been following this guide from eco...

http://www.aquariumadvice.com/forum...guide-and-faq-to-fishless-cycling-148283.html

It says to keep dosing the ammonia up when it starts dropping.
I did a little more digging and it seems like a number of things may be going on. The nitrite could be so high that the test kit can't process it and ends up reading zero. The nitrite reading could be right and the ammonia could just be slower to process due the level of filtration in the tank (aqua clear 70 set to low in 40g tank). The low pH could also have stalled the cycle.
I am going to dilute the tank water in the vial and test nitrite again tonight. if it is still zero I will probably add some baking soda to increase the pH. If it gives me a reading for nitrite then I will probably do a sizable water change to get all the levels down and raise the pH.
However if my ammonia is gone tonight I may leave everything alone and just dose a little more to see if it disappears in 24 hours.

Such a guessing game!