I have been sent a recipe that gives hop additions as: Chinook: about 30% of the alpha, add at start of boil Chinook: about 20% of alpha, add 10mins before end of boil Cascade: about 20% of alpha, at the end of boil Citra: about 30% of the alpha, at the end of boil How can I convert these...

Does anyone know Anton Paar's "Easy Dens" (density meter)? I would like to brew my first beer. I want to buy an Easy Dens, because an app can be used. What do you think about this idea? :)