I got the short one , more versatile if its short.If you can beat dinos.. you can beat flatworms. Like @Goaway said, you need to identify what you are dealing with first. Eliminating this step will increase the arduousness of your task.
arduousness-word of the day toilet paper.
my scraper works so well its been over a month since I have cleaned my glass and I can still see pretty well into the tank. .
(wait for it)