Phosban-L is a new lanthanum-based product from Two Little Fishies. 

Follow the directions carefully on the bottle to quickly reduce phosphate levels in an aquarium. The manufacturer recommends using a 10-micron filter sock with this product, and suggests dripping this product into the sock gradually over a period of hours or even days.

melev's recommendation: I've used this product a few times at 50% of the directed dose, with repeatable good results. As I've mentioned on youtube, I've exclusively used lanthanum products for the last 13 years, rather than GFO. If you've seen my reef, you know what I'm doing works.