Hey everyone, i'm new to MFK and i have a problem. I have an established tank of a year and half and i have outrageous ammonia levels. My level varies between 4 and then off the chart, my PH is low at around 5. I have tried just about everything to try and fix the issue. There are currently only 2 fish in my 90 gallon tank. I'm running a refugium sump and a cascade 1500 filter. Does anyone have any ideas to help me out ?