I have been doing biweekly water changes. Magnesium levels are 1,200. So it’s a little low, aiming for 1,450-1,500. Just got magnesium today. I got Quantum’s argonite C. It’s a 500ml bottle. The online calculator says to get it from 1,200 to 1,500 I need to dose 450ml. Is this one sitting or how often should I dose it? Capful every few hours? My auto dose broke so I’m having to do this by hand. Appreciate any feedback.