How do I make a pour over with a low flow filter?

Low flow filters are designed to increase the contact time between water and coffee grounds, which can be a powerful tool for highlighting delicate acidity or managing lighter roasts. However, because they physically restrict the speed at which water passes through the bed, they can easily lead to over-extraction if your grind size is too fine. In practice, this means you should treat a low flow filter as a variable that requires a coarser grind than you might use with a standard, faster-flowing paper.

When using a low flow filter, the increased resistance creates a more intense extraction. If your coffee tastes bitter, astringent, or hollow, your grind is likely too fine for the filter's flow rate. Start by adjusting your grinder to a slightly coarser setting—think of the texture of sea salt—to allow the water to move through the bed more efficiently. This adjustment helps maintain the ideal brew time, typically between 2:30 and 3:30 minutes, ensuring you don't stall the drawdown.

Pre-wetting is non-negotiable with low flow filters. Because these papers are often denser, they can impart a stronger papery flavor if not properly rinsed. Use plenty of hot water to saturate the filter, which also serves to pre-heat your dripper and carafe. This thermal stability is crucial when using a slower brewing method, as it prevents the slurry temperature from dropping too rapidly during the extended contact time.

Finally, pay attention to your pouring technique. With a restricted flow, it is easy to accidentally cause the water level to rise too high, which can lead to uneven extraction or grounds sticking to the sides of the filter. Use a gooseneck kettle to maintain a steady, controlled stream, and consider using pulse pouring to manage the water level in the dripper. By keeping the water level consistent, you ensure that the entire bed of coffee is extracted evenly, resulting in a cup that is both sweet and complex.