You could try a clarifier. It's a liquid binder designed to bind particles in the water to one another, making them bigger, ie: big enough to get caught in your filter. A filter sock will not work, as anything small enough to get thru your filter, will get thru the sock (easily). When I had an algae bloom last year, I had to vacuum up all the dead algae, as it would tend to sit on the bottom and not get circulated in my 24' AG enough to get into the skimmer. What type of filter do you have?