Again, if you have experience, but not currently, with rays, why did you post what you did? There are varying opinions on where to keep nitrates, but you're coming off as if you have or had experience with rays and at first, rays being stunted at nitrate levels of 50ppm. If you have credibility to where nitrates shuold be with us, please let us know. Otherwise, well have to go based upon our own experiences and what zoodiver has stated, as IMO, he is one of the more knowledgeable members and has a lot of experience.