The hozelock bioforce revolution pond filter launched into the market in spring 2013 and it proved remarkably successful. Since then it has grown in stature within the pondkeeping communityit introduces a clever new concept the filter sponges are tiny cubes rather than solid rings. Br when the pond pump is flowing through the pond filter the filter sponges work as effective debris collectors like traditional solid block sponges and are designed not to clog. Simply switch to 'waste' and switch your pump back on and watch the dirty water leave your system. Because of its effective cleaning mechanism this pressure filter can be used in koi ponds as well as ornamental goldfish ponds. Br br note uvc bulb included.quote rev in shopping basket for free delivery.