The nitrite level in my 30G tank has spike to off the charts (5+ ppm). We did about a 60% water change yesterday and an 85%+ change this morning. The levels are still insane.
About 2 weeks ago, my husband did a major overhaul of the already established tank... same rocks and plants, but brand new substrate (from sand & small river rocks to larger river rocks and some flora max substrate here and there. He also added a piece of driftwood. He left the bio filter untouched.
Also (not sure if it's pertinent), we had some danios hatch and there are several very tiny (barely noticeable) fry hanging out in the river rocks. Doesn't seem like enough to effect the nitrite, but I could be wrong. We also had 2 ghost shrimp die (which is what prompted me to test the water in the first place). I should also add that the ammonia level is at 0 and the nitrate level is a reasonable 10ppm.
I'm assuming the tank is cycling again. The problem is, there is a sick fish in there that was recouping ok earlier in the week but has taken a turn. How can I get my nitrites down in a hurry? Would adding biozyme help at all?
I don't have anywhere else to put this fish (Bolivian Ram full-grown adult)- as it is, he was removed from our other tank, because he was getting attacked by a Festivum.