Pixie

Pod machines have a small thermoblock and a narrow water path, so scale shows up as a weak, slow, spluttering extraction long before anything actually breaks.

What you need

• The maker's descaling kit, or citric acid at about 10g per litre if the manual allows it. A container for the output.

What goes wrong

• Descaling with a capsule loaded. Using undiluted vinegar, which perishes the small internal seals these machines use. Rinsing with one tank instead of two. Treating a blocked pod-piercing needle as scale when it is dried coffee - that needs a paperclip, not descaler.