i have a 55 gallon fowlr tank thats been up for about 2 1/2 months. I have about 55 pounds of live rock and 10 baby hermit crabs and one clownfish. my ammonia is zero and nitrites zero and nitrates zero and my ph is 8.4 . Is that normal I though my tank would have ammonia or nitrates or something.. please let me know,,,,, Thank you