If you physically removed the filter cartridge and placed a new one, then you removed a highly substantial amount of beneficial bacteria. Please confirm that is what you did.
Prime does not remove Nitrites and Nitrates, it only makes the water easier for the fish to be in without dying from Nitrite or Nitrate poisoning. If it were me, I would do daily 50%-75% water changes until the Nitrites get down to zero AND Nitrates go below 30 PPM
. Then only make water changes when the Nitrites increase. Once the Nitrites settle at zero, get onto the weekly recommended water changes.
> clean your filter cartridge with aquarium OR de chlorinated water
> do not leave the filter out of the water for more than 5 minutes. If need to take it out of the tank, place it in tank water for no more than 30 minutes unless kept aerated. If aerated, you can probably keep the filter bacteria alive for a few hours.
> do not change the filter unless it is degrading
> do not remove the filter without having another one in front of the old one (inside the filter) for about a week, which transfers the bacteria from the old filter
> do not do a large water change the same day that you remove an old filter
I am not assuming you did something wrong, rather giving you recommendations from what I have learned from the hobby. I may have missed something and someone may be able to add but feel free to keep updating this thread with updates.
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