Hi Tour, the Bosch dishwasher has 2 compartment behind the door. One is for detergent and the other one for Rinse Aid. The detergent, you have to add for every new washing cycle. If you use the powder type, you will see there is two line on the detergent compartment. Low and high. If its for dirty wash, just add powder until the line Full. If its half load wash or less dirty wash, just add until Low line. As for the Rinse Aid, you have to add one time only. Every time the dishwasher washes, it will only release 1 or 2 drops. Rinse Aid help the drying cycle, it shines the plates and glasses. Rinse Aid also make sure water drops doesn't stick on the surface of the plates and bowls. So, if you use rinse aid, you'll see much better drying result. We do not need to add salt in Singapore as our water hardness is low. Only apply in Europe or some countries with hard water. The salt compartment is located at the inner base of the dishwasher. Cheers, Henry Bong