Vacuum hoses connect to a manual vacuum cleaner on one end and is connected to the skimmer or dedicated vacuum line on the other. Backwash hoses are attached to the the waste line on the filtration system and is used to move water away the the filter area. The come in two sizes, 1-1/2" and 2 ". The 2" line fits over a standard 1-1/2 Standard PVC Pipe.