1) Make sure that the amount of pre-ground coffee in the filter is consistent with the amount of water in the water reservoir.
How much pre-ground coffee you use is a matter of personal taste. For medium-strong coffee, use one measuring spoon (approximately 4–5 g/0.14–0.18 oz) for each cup (125 ml/4 oz).
The strength selector button and the coarseness knob do not work when you have selected the pre-ground coffee function.
2) Increase the coffee strength by increasing the amount of pre-ground coffee, by decreasing the amount of water or by using coffee of a stronger blend or flavour.