I recently added CO2, increased my lighting to 5 watts per gallon and started (20%) to use R/O water in my 55 gallon tank. The PH has dropped from 7.8 to 6.8 which is what my PH controller is set at. Prior to these changes, ammonia level was at zero. Now it is between .5 - 1.0 PPM. Do any of these changes affect the whole system in a way that would cause a rise in ammonia?