I have tried NPX bio pellets from two little fishes and Nitraguard. Nitraguard cubes is the best out of the two I found. The bomb method works best no need for a reactor. It took about 6 weeks for them to fully kick in for the bacteria and the nitrates to start dropping. You can tell when they are working at full because they darken up. Every few months I just add a little more as the cubes get smaller. I also run GFO for the phosphate. I found the bio pellets took a long time to kick in. A few months at least and didn't do as good of a job.