Does Meds Cause A Nitrite Spike?

[Harlequins]

HI all

I upgraded my tank nearly 4 weeks ago,all seem fine,double zero's on ammonia/nitrite.

On sunday i put in meds interpet 9 for bacterial infections has a precaution,day after that my nitrite went up,not registering the next colour,(0.25) but turning it from turquoise blue to a darker shade of blue.

So i done a 50 % water change and haven't dosed again on the meds,but the nitrite is still not zero like it had been before the meds?

Any reason for nitrite to be showing after meds put in?

 

[OldMan47]

If I understand right, you used a bacterial killer in the water and want to know if it has affected your bacteria. I would not be at all surprised if it did.