Green Hair Algae Treatment

I have a tank that has been out of commission for a number of years yet still holding water and plants somehow, along with a lot of hair algae.
There are quite a number of crypt balansae which I want to pull a couple out and clean them up for a another tank that I have started to give some care to but need to make sure I can get rid of the hair algae.

My idea is to remove a few and treat them in a large pickle jar away from everything else which in my mind would allow me for maybe a stronger or more definitive treatment. Roots would be exposed during the treatment. I am just unsure what to use to not damage the crypts. ie. weak bleach solution at 5% or 10% and what duration, or another way? I also have Potassium permanganate at my disposal but no experience with it in case it can be used.

Hope someone is able to offer their experience.