how big of a water change can i do after my tank cycles?

[Isaac01]

Hi everyone and thank you for viewing/responding to my post. OK so here we go im cycling a tank and ammonia is good but my nitrites are still high. once those go down i want to do a water change but i'm unsure how big a water change i can do without triggering a new cycle... i'm afraid if i take to much water out ill take out to much of the bacteria i needed to cycle my tank. i dont have anything alive in it yet and i have very high nitrates. ide like to do a 90% water change is that going to kill my cycle?

 

[Dkuhlmann]

Wait until your nitrites are 0 before doing any wc. I would do a 25-30% wc weekly to help drop the nitrates. You can go as high IMO as 50% without bothering the tanks cycle as the bacteria that consume ammonia and nitrites are mostly in the sand and the rocks.