The molecules of detergent form a sort of framework that holds the water molecules in place in the film. If there were no detergent, the bubbles would collapse almost as soon as they are formed. You can see what this would look like by repeating the experiment, but leaving out the detergent. This experiment will not produce suds if detergent for a dishwashing machine is used. No suds are formed because automatic dishwasher detergent is formulated so that it does not form suds.
Suds create problems in a dishwasher.
They interfere with the movements of the washing arms, and they are dicult to rinse o of the dishes. The minerals that make water hard usually contain calcium and magnesium. In this experiment, you made water hard by adding epsom salt, which is magnesium sulfate. Calcium and magnesium in water interfere with the cleaning action of soap and detergent. They do this by combining with soap or detergent and forming a scum that does not dissolve in water.