My Krups Dolce Gusto coffee machine basically stopped working and I thought I would have to dump it. The machine (about 2 years old) was making all "the right noises", but no liquid (milk or coffee) was coming out. I put a sachet of the Krups Descaling powder through the system and it now works perfectly. Fortunately I had kept the instruction manual for the machine as there are no instructions on the box of powder regarding usage (I imagine this is because it can be used on various machines which could be all descaled differently?). We don't use the coffee machine very often, so I will probably do the same process with the second sachet in about 6 months time. If it's any help, my instruction manual indicates 1 litre of cold water with 1 sachet of powder but I would imagine that you could get cleaning instructions online for specific machines (?).
This product was a good price and did exactly what it said on the box - I would recommend it!