PO`d at salt mix

[LeanneP]

So this is the second time in a row that I made a salt mix from IO salt and my mg and ca have been crazy low. I just started a new box too. When I measured my mix my mg was 1120 and my ca is 360 but alk is 10.1. I just got a refractor which is reading totally different from my hydrometer so now I question which is right. For a 15 gallon mix, I added about 8 cups of salt which reads 1.026 on my refractor. To me this seems like not enough salt compared to what I used to use. How much salt are you using compared to water volumeÉ