Yes- nitrates, salinity, calcium, temp, etc and all the normal stuff but how important is it to test for strontium and magnesium and other minerals? (I don't want to buy a bunch of tests I don't need).
Mag is just as important as calcium and alk. All 3 work hand in hand.
Don't worry about strontium or any other trace element. Those get replenished with water changes.
I only have eight corals in the tank (46 gal). Any reason to test for magnisium or calcium with 5 gallon water changes each weekend? I have the following corals: two types of monti caps, two types of stylophora, a three head frogspawn, a three head duncan, a three head hammer, and a single, very small blue mushroom.
As your LPS and SPS corals grow and get bigger,They'll demand more calcium,magnesium,and alkalinity to grow and stay healthy.The bigger the colony,the more they need.And it'll eventually get to the point to where they will use more that water changes alone can keep up with.
Yotes got it. Salifert mag test is the best IMO and if you have SPS you definitely need to test mag, calc, alk and phos too, along with the other usuals.