I also used the Avent Sterilizer. After the cleaning powder used up, I would like to buy but $30 for 5 packs. Too expensive!! I went throgh the ingredient ~ just "critic acid", I used the lemon juice to clean the machine instead of powder.
I make the lemon juice and pour in the sterilizer ~ one lemon for each time. Then, we follow the cleaning procedures. After the first time cleaning, much dirt comes out.