LFS says my magnesium is at 900 which could be the reason why my dKH is low which could be the reason my Ca is low. He sold me reef advantage magnesium and told me to follow the dosing directions for beginner which say to dose 2 tsp twice a week. I went to Seachems website and their calculator says that i would need to add 192 tsp to my 45 gallons of water to get my magnesium to 1350 from 900. I said wtf. Is this right? Do i need more magnesium supplement and more spoons?!?!