I have a scale so it's not something I have tried. However, one concern I would have is that CP degrades with exposure to light, so I do my best to store it in a dark container in a dark cabinet. If you pre-mixed it, you're exposing it to light. But, that said, it is unclear to me how much light is problematic, so maybe mixing and storing in a dark container might work. I'm not sure if dissolving it would lessen its potency, but that is a different matter.