Hi, I recently got a api master test kit to test my water and realized that ammonia and nitrite were high (Ammonia is at 1 and nitrite after water change went down to .50). I have done one 25 percent water change and added ammo lock to try to protect the fish that are in there. I just want to know what would be the best next step to help the problem before my fish die. Also how long do I have to fix this before my fish and snails die? I am really worried about them dying.