I just tested again and the FC is at 22ppm and the CC is at 0.5ppm. I'm not losing >1ppm FC, but my CC isn't 0 either. I brushed the sides and floor again for good measure. I'm assuming I should keep the current course of action...keep FC > 20ppm until CC - 0? Keep brushing sides and floor? What about adding DE to the sand filter...would that help at all?