Algae Problems

[Palster]

I am doing a 25 gallon water change tomorrow morning with R/O water (just finished mixing the water) As for circulation I have a pump in the sump moving about 700 gph after elevation loss is factored in and I also have a fairly large power head in the tank as well. The purple slime algae does seem to collect in the areas with the least water movement though. Should I be able to get a PO4 sponge at most aquarium stores?