Turns out Ammonia is at .5ppm. I tested last week and it was at 0ppm. My Fx5's impeller broke the other night and I bought another Fx5 the next morning (didn't want to wait for shipping on new impeller). I left the media baskets in the tank over night so perhaps I lost some bacteria during the transfer? Anyway, I did a water change and moved some of my stock to balance it out until the new filter ages a bit. Hopefully things continue to improve as I've noticed less open mouth breathing already.