From my previous post you can see my motoros are doing great. all the parameters are excellent except for the nitrate. I can't seem to get it below 30-40 ppm. I am doing at least a 40 % water change weekly and last week i did two 40% changes. I have also added Seachem's denitrate and i have started growing pothis out the top of my aquarium. Any additional things i can do?