most likely its red slime, its bacteria. sometimes they can have hair like features.
a picture could only prove further.
all irritating algaes, minus away coralline, and red slime could only be reduce with lower nutrients in water. nutrients in the sense of P and N.
the phosphate and nitrogen based.
do water change, add more rowa or smilar.
normally i will do the above + sucking it out or blasting it will a pump or turket blaster
if its really red slime bacteria, u can use antibiotic available in LFS as red slime remover. but please dun use it for u dunno what else it will kill.
all the best.