Black algae is persistent and takes dedication to get rid of, but it is not an indication to get your pool acid washed. Acid washing is indicated for cases of mineral scaling (even this is arguable) but not for algae eradication.
Try reading Defeating Algae to get you pointed in the right direction. Basically, you need high levels of chlorine, water circulation, and lots and lots of brushing.
Have you read Pool School yet? There is much information to be had there. When reading it, you'll begin to understand why you got algae in the first place, how to get rid of it, and how to never have it again.
Nope...shock and scrub. But from your other thread, if you are draining your Pool...just take care of it then...bleach will kill it if it organic...I would think the acid would do a number on it too if you go the route of an acid wash. Question though...can you give us some back ground...why do you want to drain/acid wash the pool?
The trick with Black Algae is the brushing - they have a tough outer shell that is resistant to chlorine. By brushing it, you knock the heads off so the chlorine can attack the insides. The outer layer can re-establish so you have to brush daily if not twice a day. The pool store will try to sell you a bunch of various 'treatments' which won't help and will likely make the situation worse. So just remember, chlorine and brushing. Lots of elbow grease.