Lactic acid is better for most coffee machines as it is less corrosive to plastic parts than other acids and has a good effect. Although sulphamic acid is very strong and fast, it can be harmful to the environment and should not be released into the environment. Lactic acid is also well tolerated and a good alternative as it is milder than vinegar.
Lactic acid
Advantages: Gentle on plastic parts and seals, well tolerated and inexpensive.
Disadvantages: Slower than sulphamic acid.
Application: Dilute 80% lactic acid with water (e.g. 1 part acid to 1-2 parts water) and add to the water tank.
Sulfamic acid
Advantages: Very strong and fast descaling, which also copes with shorter descaling times. Neutral in taste.
Disadvantages: Environmentally hazardous as it is not easily biodegradable. Can cause skin irritation.
Application: Use special descaling agents based on sulphamic acid and follow the manufacturer's instructions.
Recommendation
For most household coffee machines, lactic acid is the better choice as it is gentle on the materials and offers sufficient descaling performance. Although sulphamic acid is more effective, its negative impact on the environment should be taken into account. Only use sulphamic acid if the machine explicitly requires it and you are aware of the environmental risks.
Does what it should
It descales well