The filter helps not to let the machine calcify so quickly. The filter must be changed every 2 months, unless the machine 2 weeks at a time is not used, then the filter must be replaced. Otherwise I find the installation quite complicated. The manual is easy to understand. But the filter attaches itself not as "easy" fully described. You have to press a little so that absolutely no air in there in under water. Only then start the engine to pump water.