Review on Seachem PhosGuard 100 mL Bagged - Product Review, Benefits, and Usage Guide by Carrie Millemann

Have been using this for many years when I have had problems with black bristles/beardweed and cyanobacteria/blue-green algae. It works great and I've been using it ever since. The mesh pocket makes it very convenient to use. You simply place a pre-filled, sealed pouch in your filter without the mess of bulk-packaging. It removes phosphate from the water very effectively and claims not to put the removed phosphate back into the aquarium. I use it in a freshwater aquarium in a small external filter. One of those things that make life easier!