Live Rock Question

Last week I was given about 70lbs of Fiji live rock from a friends tank that
has been turned off and ignored for approx 4 months. This friend shut down
his tank completely leaving the rock at approx 68 degrees with no light or
skimming.

So I took the rock off his hands and brought it home. Hope to use it for my
55 gallon FOWLR Trigger/Puffer tank. The plan is to add 40lbs of live sand
and then the rock.

The problem is that most of the rock is covered in a light green colored
algae. I'm in no real hurry to use this rock however there are a couple of
small pieces I'd like to add to my display reef tank. I am leaving this rock
in the bucket at 77 degrees and a powerhead keeping the flow going. Also I
leave the bucket covered so the rock is in complete darkness 24/7. Will this
algae eventually die off or do I need to scrub it off and go from there?
Could any of the invert life have survived the long term neglect? I truly
expected some sort of spike but then again it's only been a week or so. It's
beautiful rock and the best part is that it was FREE!! WOO HOO!!!

The bucket water looks like:
77 degrees
Ammonia=0
Nitrite=0
Nitrate=0
Phosphate=0.1
pH=8.2-8.4
SG=1.025
Haven't checked CA yet. I've been dosing the bucket with "Purple Up" I doubt
it will do any good by I figured why not ...

Pretty much the same as in my display tank! I can't get PO below 0.1 to save
my soul!! Any suggestions?

dosing purple up in a bucket thats getting no sunlight wont do jack. algae
is photosynthetic: it needs sunlight to make itself. simply dosing purple up
w/ no light wont stimulate coraline growth.

sides, if its green algae, its safe so long as its not hair algae or any
nuisance algae. id add at least a floro light if you want coraline to cover
those rocks again.