get a UV filter, you will never regret it!!!
my 1100g was so green i couldnt see more than 2" into the pond, and 4-5 days of running 1000gph pump through a UV, and it was 99% clear, and has been ever since (this is my 2nd summer)
but yeah, some people say the straw like product works well. i think it takes a few weeks?? i havent used it though