oh dear, please don't treat it with rid ich (you got fish in there, right?)
and washing your gravel...wait, you got fish in there?
well, either way i wouldn't treat it and planaria worms are usually a symptom of overfeeding, so once you get feeding under control (ie. not in excess) you should have the problem taken care of.
if there are just a few, your fish will eat them, i think. i used to have those, then i stopped overfeeding, and they went away.