I was thinking of using one of these as a pre filter on my system. By chance I came across the instruction sheet for them on the web and noted two things; 1) They cannot cope with blanket weed filaments and it is recommended that the unit be disconnected for 4-6 weeks during BW treatment hum ! 2) The bypass that comes into use when the unit is blocked must be returned to the pond not to the inline UV/biofilter (I checked with Hozelock customer support and they confirmed that you cannot simply use this to bypass the filter it has to go to a low pressure outlet i.e. back to the pond). So it is easy to finish up with an overheated UV and a dead biofilter.
So I am not buying one….. anybody any experience of these, I hear they have been around in Australia for a while ?