Could These Test Results Be Right?

[Lizzie71]

I posted a few days ago about losing a few fish due to a sudden nitrite spike. This may well have been caused by an anti-bacterial medicine, but whatever it was, it was clear that I was going through some sort of mini-cycle.

I have been doing plenty of water changes, and today I am reading 0 nitrite I am doubtful whether this could have righted itself so quickly - could this be the case?

Nitrites were 3 on Monday - 2 x 50% water changes
3 on Tuesday 1 x 50% water change
0 this afternoon - did another 50% change anyway.

I was wondering if the reduced bioload (due to fish deaths) could mean that the filter is coping better now. Stocking is now

1 guppy
2 platys plus 1 2 month old fry
2 amano shrimps
2 otos

I won't be replacing the lost fish for a while, just in case, but I do eventually intend to add two more fish, probably a platy and a guppy to replace those we lost.

Ammonia has been 0 throughout, nitrates around 20, temperature 26-27.

 

[Colin_T]

The ammonia and nitrite levels can quite literally drop overnight. The bacteria levels get to a point where there are sufficient numbers to break down all the waste produced. At that stage you can have a high reading one day and the next it will be zero.