If you really want to get rid of the unsightly stuff, catch the FHs and put them in a spare tank. Then clean and either use a cup of clorox or saturated salt solution to disinfect the tanks and anything else associated with it including filters and rocks and sand and wood. I prefer the saturated salt solution as it is instantaneous and residual does not affect the tank when you refill, in fact you probably do not need to rinse out the salt just drain out as much as you can and refill. Planaria and any worm can only last about a minute in contact with saturated salt solution, so give it just the time it takes you to wipe down all surfaces with the solution, which should be more than enough time to kill the unsightlies.
I did write an article on this which is on my website.