What I did was put magnesium chloride (magnesium oil) into a bottle of club soda. Club soda is plain carbonated water.
The dosage for magnesium chloride is 7 drops per day. So I put 35 drops in a 10 oz bottle of club soda. Immediately cap the bottle and shake for about 45 seconds, then refrigerate for several hours before using.
5x7 is 35 so there will be 5 doses of magnesium in the bottle. 10 divided by 5 is 2, so I pour out a two ounce dose each day.
This seems to work well. But I wonder if I am really making magnesium bicarbonate out of magnesium chloride. The original magnesium bicarbonate recipe uses magnesium hydroxide (Milk of Magnesia) to make magnesium bicarbonate.