I have a 26 gallon Bow Front tank with 4 Zebra Danios & a baby Pleco in it. I have added live bacteria solution (Microbe Lift Special Blend) to the tank once a week. I have a liquid master test kit and it indicates that my ammonia levels are 8.0ppm and after 5 weeks still now signs of any Nitrite levels. I do once a week water changes of 3 gallons. Any suggestion on what I can do to solve this problem?