Low salinity...yup they do this to save on salt mix and also likely to help suppress fish diseases. Some LFS's keep the majority of their corals in a system separate from the fish and at a slightly higher salinity.
So good to hear it is like all that science I took in school taught me... respiration is just a continuation of metabolic processes like active photosynthesis.... Thanks for putting all the words down Greg, I have two kids and little time...