About two years ago, it started to confuse the waters. You open the filter, it runs and from the other side and vice versa. I spoke with the company's technical support and they told me that I need to replace some orings (rubber rings) that exist in the neck, costing about 25€. I found them in the market for only 1€ and they lasted only a month. Inevitably, I will have to spend 25€ on orings every 2-3 years.