Probably dumb on my part but I bought another canister filter (Sun Sun 704b) to go with my existing Cascade 700 canister and my Penguin 200 HOB filters. I was in the middle of cycling the new 75 gallon tank when I added the large Sun Sun canister filter. I wanted a lot of filtration because my goal is to stock it with a lot of MBuna cichlids. I was about three weeks into the cycle and was seeing Nitrites rise as well as Nitrates starting to show readings all the while keeping my ammonia at around 3 to 4 ppm. After I added the new filter and waited a couple of days my ammonia was at 1 to 2 ppm but Nitrites and Nitrates dropped back down to 0 ppm. My PH has remained at 7.8 to 8.0 all along and is currently at 7.8. Does this seem right? Why would the Nitrites and Nitrates disappear with the addition of more filtration and no water changes?