This video will focus on magnesium which is an often overlooked ion in our reef tanks. Reef hobbyists interested mainly in stony corals tend to tunnel vision in on calcium and alkalinity. On one hand, that makes sense because coral skeletons are primarily made up of calcium carbonate. On the other hand, it’s an incomplete view of what’s happening in our water and, keeping those levels can be challenging despite our best efforts. Here is where testing for Magnesium can help.