This is what I use.
10 table spoons to 450ml of ro/di, shake well. I use a plastic mason jar. I just shake the jar before I use it and pour 5-10ml/50g of tank water into a graduated cylinder mix in the other stuff if I am going to let it sit for 5-10min giving it a swirl every few minutes and dump it in the tank. Power heads on but return pump off let that float around for 20min or so and turn on the return. I usually do it Friday nights a couple hrs before lights out. Next day crystal clear, except where I didn't clean the glass well.....