For macros, I mix it up in large batches and just let it sit.
For traces, I mix it up 500 mL at a time. Lasts 6 weeks or so. I don't refrigerate it. By the 3 week mark I start seeing a little fungus, but I never have any problems.
For traces, I mix it up 500 mL at a time. Lasts 6 weeks or so. I don't refrigerate it. By the 3 week mark I start seeing a little fungus, but I never have any problems.