Weak Chemex coffee, watery and lacking body, is a common complaint. The Chemex’s thick filters demand more from your technique than other pour-over methods. Here is how to find the problem.
Check your ratio first
Many Chemex drinkers underdose. The Chemex paper is significantly thicker than V60 paper and absorbs more water during brewing. A 1:17 ratio that works for V60 will produce a thinner cup in a Chemex. Try 1:15 instead. For a 6-cup Chemex: 50g coffee, 750g water.
Grind finer
Chemex needs medium-coarse grind, not coarse. The thick filter slows water naturally, so a too-coarse grind causes water to gush through without picking up enough coffee. Grind closer to V60 setting. If your brew finishes in under 4 minutes for a full 6-cup batch, your grind is too coarse.
Rinse your filters thoroughly
Chemex filters are notorious for adding paper taste. Use significantly more rinse water than you would for V60. For a full Chemex brew, rinse with 500ml of hot water before adding coffee. Discard the rinse water, then start brewing. Skipping this step alone can ruin a Chemex cup.
Brew time check
A 6-cup Chemex brew should take 4 to 5 minutes total. Under 3:30 is too fast. Over 6 minutes is too slow. Time is the most reliable signal that your grind and pour technique are in the right zone.
Pour technique
The Chemex bed is wide. Pour in slow, deliberate concentric circles to keep the bed level. Aggressive pouring creates channels where water bypasses the grounds. A gooseneck kettle helps significantly.