1569Filter paper is placed in the circular outlet of the top container of the vaccum water filter. a water sample is poured into the container. a vaccum is created in the bottom container by pumping air out using the pistal grip. water is pulled through the filter paper by the vaccum. microorganisms in the water sample are caught on the filter paper, the sample water is drips into the bottom container. this water filter will remove phytoplankton from a water sample to measure chlorophyll a.