If you have a pond and have problems every year with blanket weed you need this stuff. In the last 20 years I've tried all kinds of chemicals, barley straw and treatments but Cloverleaf Blanket Answer is the best I've come across. It doesn't harm aquatic plants like some treatments can as it's not an algaecide. This is an enzyme and eats away at the algae. Within a week you can see it's benefits even on waterfalls and pebbles which normally get covered too. I've been using this stuff for the last 2-3 years and you should too. Available in different sizes to accommodate your pond size. The best bit is it generally only takes one treatment per season, twice at the most!