It's really sticking around? I guess you don't have a lot of skimming/mechanical filtration/filter feeders around - I can dose a few hundred mL to my system and have it clear in 30 mins
It shouldn't harm things, even in terms of blocking out light for other phytosynthetics it shouldn't be too bad, and it should promote explosive growth of copepods, so if you've got any microfauna in your system, they should be able to take care of it. Heavier skimming, mechanical filtration with a very fine filter sock (<10 micron), or just a water change will get rid of it, but I would just leave it and let whatever can eat it pig out for a while.