How do I work out how much formula is required?

When you are filling the clean water tank on your machine, you will notice measurement lines on the back of the tank - one for water and one for formula (some formulas also have a measuring cap), to ensure you are using the correct amount of both. When cleaning large areas that require more than one tank, it is best practice to let the tank empty before refilling with fresh water and formula to ensure the mix is balanced to recommendations.