We bought our home at the shore 2 years ago. We have a composite deck--Trex I think--and we have severe green algae in the shaded areas. Each of the past 2 summers we bought different brands of cleaners, and both have been disappointments....lots of manual scrubbing and only marginal improvements when we were finished. What a difference this year with Corte Clean! With only one treatment at full strength and scrubbing with a brush, the algae washed right off, like magic! We could not be more impressed. We even have enough material remaining so we can use it again next spring because we expect to use this product for a long time.