I have a 150 gallon cichlid tank with 22 peacocks of varying sizes from fry to full adults and 3 catfish. This tank has been set up for about 4 months and was upgraded from a 75 gallon (set up for over a year) with the same rock, filters (hob seachem tidal 110 and a magniflow 160) and gravel from that tank. I did add a new additional magniflow 160 to the 150 tank when I upgraded. I tested the water then and everything was fine. The last few days I noticed one of the fish was loosing some of its color and then actually died. I had become lax about testing since everything was on "autopilot". Tested yesterday and ammonia and nitrites were zero but the nitrates were off the chart. I did a 50% water change yesterday and then did another 50% today and the test kit still look like it is slightly over 160ppm. Should I keep doing 50% water changes daily to bring it down or should I be more aggressive or slow down since they are somewhat acclimated to the high nitrates? I typically do 25% water changes a week and clean the filters once a month and feed twice daily. I know now I need to do more frequent filter cleanings and cut my feedings from twice a day to once a day. Any other suggestions would be greatly appreciated!