Question
My pond (20'x12'x4'deep) was full of stink grass/musk-grass chara algae
until I raked out most of it. I then drained the water and removed most
minnows, platys, shrimp, 2 perch, and a gar. Next I added water and
added copper sulfate incrementally until filled. I'm sure I used too high a
dose but worried it may affect live oak and bald cypress roots. My main
question is whether 24-36 hour exposure enough to kill what little chara is
left along with spores if I drained it tonight or morning? After draining
completely is it necessary to treat the fish I removed to kill spores directly
before putting in pond?

Answer
Dear Josh,
As a koikeeper myself I never want to use copper sulfate as it will damage the fish.
The copper sulfate will build up in the liver and never can be reduced no more so one time it is going to be to much and the fish will dye.
However you did good to remove all the debris, this is the best way to go as if there is no or less debris and no dissolved debris, the algea have no food.
I personally would advice to remove the fish and place them in quarantine with some of the pondwater.
Then clean the pond
add water again into the pond and let it run trough the filters some time.
Place fish back by placing them in a bag with the pondwater
let the bag drift on the water for approx 30 minutes or so and then ad some pondwater in to the bag.
This will give the fish the change to adjust to the new water.
Ten get the fish out of the bag without getting the bagwater in to the pond.
Watch the fish closely and done!
A good filter will help you against the Algea.
If it affects the plants and trees... depends on the dose.
However if it is to large personally I think the best way to go is to reduce this by flushing some water out.

good luck and happy pondkeeping.
Raf