Grind size affects how quickly water moves through coffee and how easily flavour compounds dissolve. Finer is not always better.
What to know
If a brew tastes harsh and dries the mouth, try a slightly coarser grind. If it tastes thin or sour, try a finer grind or a longer contact time, changing one variable at a time.
Practical takeaway
Record your dose, water amount and grind setting so improvements are repeatable.