I have API
pH,
NH3,
NO2 and
NO3, Salifert
Ca,
Alk and
PO4, and Seachem Reef Status Mg which also includes tests for carbonate alkalinity, borate alkalintiy and total alkalinity. The Seachem kit is designed more like a laboratory test i.e. filtering the sample before testing. I no longer work in a lab so I don't have access to lab grade tests to compare them against but it makes me think it might be more accurate.
