Chloramine and Aqua Plus
Comparison of Water conditioners
I suspect your water conditioner is not sufficient for chloramine treated water.
Do a test, add tap water to a bucket, test for ammonia (should be zero). Then add the appropriate amount of your water conditioner. Then test for ammonia again. If you find ammonia, you know you have chloramines in your water and the water conditioner is not aboe to treat the ammonia released.
So, your water change is just like a big shot of ammonia, more than you were adding before and so the nitrite consuming bacteria are unprepared for it.
IMO, I'd go buy something that absolutely treats the ammonia as well as everything else but without locking it up so tightly taht the cycle is stalled for lack of ammonia. I use Prime. Just my two cents.
Comparison of Water conditioners
I suspect your water conditioner is not sufficient for chloramine treated water.
Do a test, add tap water to a bucket, test for ammonia (should be zero). Then add the appropriate amount of your water conditioner. Then test for ammonia again. If you find ammonia, you know you have chloramines in your water and the water conditioner is not aboe to treat the ammonia released.
So, your water change is just like a big shot of ammonia, more than you were adding before and so the nitrite consuming bacteria are unprepared for it.
IMO, I'd go buy something that absolutely treats the ammonia as well as everything else but without locking it up so tightly taht the cycle is stalled for lack of ammonia. I use Prime. Just my two cents.