- Mix one sachet (10 grams) of citric acid with 200ml of water. Pour into the empty unit – Do not put the lid on – Switch on for 1-2 minutes. Plug off from mains, leave to stand for 30 minutes – Drain and rinse unit. Run a full cycle with baskets/racks inside and lid on using exactly 90ml of water. DO NOT USE any descale that is not Citric Acid.