Low Magnesium levels

So I've had my 75 reef up now for a little over 3 months. All of my levels have been good the entire time, except my magnesium seems to be a little low. All of my corals look great, so maybe it's not a big deal, but wanted to see when I should be concerned that it's too low?? Also I have very good corraline growth



Levels

Dkh- 12

Calcium- between 400-440

Magnesium- between 1125-1180



Corals- mushrooms, Zoas, toadstool, torch, and hammer



Thanks!