How do I descale the Dinamica and how long does it take?

When 'DESCALING NEEDED PRESS OK TO START (~45MIN)' appears, press OK and follow the on-screen steps: remove the water filter, add one 100ml pack of De'Longhi descaler to level A in the tank and fill to level B with water, then place a 2-litre container under the spouts. The full descaling cycle takes approximately 45 minutes and includes automatic rinse cycles; only De'Longhi descaler should be used, as unsuitable products can cause faults not covered by the warranty. (Page 18-19)