That must be an error of some sort. This recipe is just a revision of my 3 part with sodium hydroxide. The other thread is a revision of Jim Welsh's true two part recipe. I assume you mean this recipe: https://www.reef2reef.com/threads/new-diy-two-part-recipes-with-higher-ph-boost.344500/ The calcium part in that recipe contains about 8,300 mg/L of magnesium (when made correctly). To boost a tank from 1150 ppm magnesium to 1500 ppm magnesium (350 ppm) would require the addition of 4.2% of the tank volume in additive, so you'd have to have added 4.2 gallons to a 100 gallon tank. I assume you did not do that? (if you did, salinity would rise a lot and magnesium would decline when you returned it to normal).