My salinity is now 30ppt I did a water change yesterday. When should I be seeing resultsWhat has your salinity been increased to now? Hopefully it fixes your magnesium issue, you will probably see an increase in cal and alkalinity as well die to using more Salt..
Magnesium would be the least consumed of the 3 but alkalinity and calcium work with and against each other. Depending of what corals you have, generally at the start every water change is enough to keep levels at a good point.
But when you start adding life and corals they will start to be consumed and will need to dose every day to keep it at a good level without large swings in your parameters.