Nitrite rise after fishless cycling

G

gali

AC Members
Feb 22, 2005
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Lexington, MA
My new 38g is finally cycled. I went fishless, it's taken about 6 weeks, but last week I finally got readings of 0 ammonia/nitrite for 4 days in a row and nitrate was quickly rising. It looked like it was finally done!

I did a large water change, refilled, tested - evertyhing looked ok. Went to lfs yesterday and got 2 cories and 6 small tetras. I wanted a pair of pearl gouramies as well, but they didn't have any. So I decided to start with these even though I know I should have added a full bio load.

I'm glad I didn't. I tested the water last night:
Ammonia 0 Nitrite 0.25 Nitrate 10
Did it again tonight -
Ammonia 0 Nitrite 0.5 Nitrate 20

I did a partial water change, got nitrite back to about 0.25, nitrate to 10.
Fishies seem to be pretty happy. They're very active and all came out to eat when I fed them.

So now I'm worried. I though fishless cycling would eliminate these fluctuations. Is this normal, or is there a real problem?

TIA.
 
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nitrite gradually went up to about 3 on week 2, stayed up for a loooong time then started going down again. it finally tested 0 for 4 days in a row last week and nitrate went up really high.
did i misinterpred anything? i thought the cycle was done :confused:
 
Sounds like it should have been. Did you continue dosing ammonia during those 4 days?
 
i did, up until a day before the water change. could it be leftovers from the last ammonia dosage?
i'll keep changing the water. any other advice?
 
As long as the dosing was consistant, I doubt any would be leftover. Any changes otherwise? pH or KH? Filter cleaning? The nitrite populations are slower to develop, but usually pretty stable once they reach the needed colony size.
 
the only thing is tempeatue. it'd been at 82 and i lowered it to 78 the day i got the fish. but could that really be the reason??

other than that, it's all the same.

anything i can do except for water changes and keeping my finges crossed?
 
i always get upset if a thread i read is not finished, and i don't find the answers to the questions that bothered me.

so, in case someone's reading this and needs more info, here's an update of the situation:

after 3 partial water changes and constant monitoring, nitrite went down to 0 everything looks ok now. all 8 fishies are ok, including 2 cories that kept me worried in the first few days since they kept hiding and looked stresses. perhaps they were, but i think they're ok now!

i'll give them all about a week or so, then try to add a few more and see what happens.


:D
 
Sounds like the added bioload produced more ammonia than you were adding and since the nitrite converting bacterium are slower to develop they couldn't process the spike fast enough to keep the water clear.

Good thing you didn't jump to a full load. :)

Pics?
 
I have a 37 gallon and just finished cycling and stocked the tank. I had a period where it stalled and nitrite didn't change. I had to perform a water change (80%) and slowly add amonia again to get the nitrite going properly.

When nitrite went to zero, nitrate went super high. I did a couple more water changes and only added amonia every third day, it was all processed out in a few hours. Then I did no water changes and still added on the third day but quit testing for 4 weeks. Strangest thing was, nitrate no longer existed in the tank after that 4 weeks. My guess, the small amount of algae that developed ate it up...dunno.

I just did a 100% water change and stocked the tank on tuesday, everything is good so far. No cloudy water, no rising levels on anything but I've only fed for two days and have heavy filtration. First time I did fishless in all these years and was surprised at the result. I used to just fill a new tank with water changes from my other tanks but didn't have that option starting new this time.

Good luck and my suggestion is to just forget about fish until you're absolutely certain your tank is cycled.
 
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