Even if you have a good test and it works to add magnesium based off it, adding a higher amount all along, and confirming it by testing if you want, will also work with less magnesium decline due to the deficiency in the AFR.
This is true but the only thing i keep steady is alk and dose or dial back dosing afr based on that. The others i manually dose based on testing at a less stringent rate. Alk i test every few days. Calcium mag phos nitrate iodine every couple weeks. Then dose based off that.