Yesterday I checked my water and it had sky rocketed from perfectly safe to almost toxic in a few days. I did a water change on Sunday all the water levels and everything were fine. I didnt add any fish in and was wondering why the ammonia/nitrite could have skyrocketed like it did and how do I go about getting rid of it before it kills my fish? I have put AmQuel+ in it temporarily and it is supposed to detoxify it but how do I get my levels back to safe?