PoolRx 101055 Black Spa Unit Swimming-Pool-Algaecides， 400-1000 gallon<div style="text-align: left;"><strong>[Product Information]</strong><br><ul><li>Simply place in pump basket or skimmer basket</li><li>Eliminates all types of Algae</li><li>Reduces Chemicals</li><li>Effective for up to 6 months</li><li>Simplifies Pool and Spa Care</li></ul></div><img src="http://ecx.images-amazon.com/images/I/61ttK7PmrSL.jpg" noproxy>