page 5 your using seachem denitrate reactors, page 30 your installing a biopellet reactor and I think somewhere there was a pic where the apex was monitoring sulfur, which would imply a sulfur reactor. So what are you using ? which was better? I used a biopellet reactor for years which worked well so long as I checked for blockages , pump failure and medium level. If any of the fore mentioned occurred it set it back weeks to get it back to where it was.