45 Gallon Fish In Cycle Help Please!!!

[VictoriaC]

45 Gal pentagon Corner tank - set it up with silica sand substrate, mopani driftwood and some live plants. Let it run for 24 hrs and then added filter media from existing established tank and adult molly with 4 molly fry ( 4 months old or so)
For some reason i thought this would be enough and a week later my readings where fine with nitrates at almost 5.0 so i thought it was safe and added a cory, 2 shrimp and 2 ottos. Now 2 days later i took a reading and i got

Ammonia .25
Nitrite .25-.5
Nitrate 5.0

Decided to do a water change of 15-20%
Two days later my readings:

Ammonia .5
Nitrite 1.0
Nitrate 5.0

Thinking about moving cory and ottos back to 10 gal...

Did a water change yesterday and today my readings:

Ammonia 0-0.25
Nitrite 1.0
Nitrate 10.0

And interesting thing - up untill today my PH was 8.0-8.2,
Today its 7.8-8.0

Fish is all alive and swimming all over - cory darting up and down ( can it be due to not enough oxygen?)

Please advise on what to do?
Should i do another change today? Or should nitrite drop already?
Can anything else cause nitrite to stay high?

Thanks!!

 

[VictoriaC]

Oh i also have a bubbler, and filter is aqueon set on high - so it agitates water well to keep it more oxygenated...

 

[VictoriaC]

Today its
Ammonia 0
Nitrite almost 2.0!!! ( very bright magenta)
Nitrate 10.0
PH is a clear 7.8 - it was always 8.0-8.2 in this tank and the other one i have...
what is the reason for it to drop?

Anything else besides water change ( or i would say in addition to water change) - that can be done????

I moved ottos back to 10 gal

I also found snails in this new tank - have no idea where it came from! as the plants and decor that i placed in a new tank where previously in my 10 gal, and my 10 gal has no snails..hmmm

 

[librarygirl]

It's likely the media you added had enough bacteria to sustain the molly and the fry. When you added more fish, the bacteria now need to multiply to adjust to the heavier bioload which in turn causes toxin spikes.

Cycling can cause PH fluctuations; have you tested your tap water? Test it out of the tap and then let it sit in a glass for 24 hours (stir it up occasionally) and then test PH again; this will be your true PH; sometimes it changes from what's in the tap (for example out of the tap my PH is 8.4 but once it degasses it goes down to 7.2 which is what my tanks' PH is).

There isn't much you can do other than testing and water changes; try to keep nitrite <.5 as it's toxic to the fish at high levels) until the bacteria catch up.

Corys tend to sprint to the surface to gulp for air and they sometimes play around the glass, shimmying up the glass and then back down which is normal. If they're gulping at the surface very often then it might be because of the nitrites. How high is the temp of the water? What type of Cory? Some Corys like pandas like it a little cooler than most tropicals, low - mid 70s but a little higher shouldn't bother then too much (e.g. 77-78). Usually the water flow from the filters provide enough oxygen exhange; you could add an air stone to increase the agitation if you think it's an issue.