HTH Algae Guard Ultra Algae Control 1 Qt.

Strong algae control formula that provides up to 3 months of protection. The non-foaming, non-staining and fast-acting formula both kills and prevents extreme amounts of stubborn green, black, and mustard algae for a season of crystal clear pool water. Simply add directly to your swimming pool water and dive right back in. Compatible with all swimming pool types and works great with HTH shock products.