High ammonia level in fishtank.
I've have a 55 gallon fishtank I got 3 weeks ago. We have been adding fish once a week. (I know now that was a big mistake) A few days ago, a couple of my fish got sick (loss of appetite, color loss, staying at the top of the tank, etc). One fish has died but 2 are still sick. After researching I realized it was ammonia and nitrite poisoning. Yesterday was the first time I tested my water. The ammonia was off the charts, past 7.5. My nitrite level is 0.2. Yesterday we did a 25% water change. I also put in those ammonia tablets and something called "bio spira" which is nitrifying bacteria. Today my ammonia is 5.0 and nitrite is still 0.2. I was told to do 10% water changes every day until it get better. I would like to know if I am on the right track and how long it will take for my ammonia and nitrite to reach zero. Also if there is anything else I can do to speed up this process...