I call it Hair Algee oddlly enough, uhh I am shure theres a scientific name for it but I dont know it, it dont think the algee itself is a problem but it might be a sign that your water has a high nitrate content, which is a problem,,,,,,,test your water...if the water tests ok then the only problem is esstetics (spelling) lol but if you dont mind the look then go for it
Thanks
Jordan