I've kept the co2 at 30 ppm or a bit higher for the last 3 months. I use the co2/kh chart and keep my ph at the right level to achieve the 30ppm. I also have a lamotte co2 test kit I occasionally use to double check my levels. Having high co2 levels was one of the things I had read about early on when I had this problem so I've kept a close eye on that one. My plants all do well, usually the water looks like a glass of 7up with everything pearling and growing well. Nitrates between 5 and 10ppm, phosphates between .5 and 1ppm. My nitrate kit is a lamotte, I use a red sea phosphate kit and have double checked my phosphate kit with another red sea kit to verify results. As far as I can tell everything is in order and this stuff should be clearing up but it just goes on growing on about everything. I trim the bba coated leaves every week and vacuum the fallen algae from the gravel. There is no trouble with any other type of algae, even my glass stays pretty much algae free.