A removable filter for separating and filtering slurry liquid from solid particles includes one or more filter sections connected by a filtrate conduit. As a skilled artisan would readily understand, the sub-munitions is one type of rotationally sensitive device. The methods include the addition of the lanthanide compounds to the bulk of the pool water, but preferably involve the loading of the pool filter with the composition and the circulation of pool water through the filter to effect the removal of dissolved phosphate in the water.