I have a 40 breeder with a good quality skimmer and a carbon reactor. I don’t use any nutrient lowering methods besides water changes. I have a pretty decent size bioload as well. For whatever reason tho even though I can’t get a decent nitrate or phosphate reading. There is hardly any algae as well so it’s not like the algae is just consuming it before I can test. The reason I wanna get this figured out is that the low nutrients are causing corals to bleach as well as causing what either is cyano or Dino because of the lack of nutrients. Could nutrients be binded up in the sand bed? Thanks for your help