I bought this from Todd @ Cherry Corals and never used it.
There are a few threads in the Fauna Marin and Cherry Corals forums on reefcentral, it is supposed to be very effective in getting rid of all nuisance algea. I paid around $40 with shipping, asking $30 cash



"Ultra Algae X is a very strong and effective solution to remove any hair or plague type algae growth in Reef Tanks, it also removes dinoflagellates and Bryopsis algae. It treats algae plagues in reef aquariums without harming any corals. Algae X does not destabilize the aquarium system. Algae X is not a treatment for Cyano bacteria."