You don't.
You ID the algae type and address the root cause. Once that issue/the imbalance that's causing the algae is sorted, the plants will take care of it for you. Cleaning or adding new stock to take care of algae is a waste of money.
I've found with Java you can often rub the leaf between your fingers to clean it off.
Depending on the algae type you can sometimes "spot dose" liquid carbon to kill it too.
You don't.
You ID the algae type and address the root cause. Once that issue/the imbalance that's causing the algae is sorted, the plants will take care of it for you. Cleaning or adding new stock to take care of algae is a waste of money.
....you'll probably want to clean the algae off as part of this process.....