Nitrates never got above 5ppm over a week as I was doing 50% w/c's EVERY day. Since the BCB's have been in I now only do 50% every second day. The test will be in another 3 or 4 weeks when I see what happens with the nitrate readings after w/c every 3 days then 4 and so on. I aiming for 1 to 2 ppm with a w/c one a week or even every second week.