No magnets. No poly-phosphate. No electro-magnetic waves. Most of the solutions offered by technicians do not actually work.
The best solution is the cheapest solution.
Just put in citric acid and synthetic vinegar once every three months. They will remove the calcium and magnesium from the machine’s heating element. Voila!
Pour in 100 grams citric acid or half a bottle of synthetic vinegar into the detergent drawer. Put the machine on the hottest setting. Once the cycle is complete run the machine on a cold cycle. This ensures that all the citric acid and vinegar is out.
1st, 6th and 12th month use citric acid. 3rd, 9th, and 3rd month use synthetic vinegar. Thus, you are cleaning the heating element every three months but using each of the products once every six months.