I don't mean to hijack your post jonzo1, but I have a major algae problem as well. I have a 75 gallon tank with 288 watts of lighting. I run my lights 8 hours a day. My salinity is 1.025, my nitrates and nitrites are near 0ppm, my phosphates are at or below 0.03, I have a protein skimmer on this system as well. I also have phosguard inside a module that the return line is attached to. So, does anyone have any idea as to why I have such a big algea problem?