This is an effective approach for removing algae on hardscape: wood and rocks. Avoid this method for plants.
This is our usual approach to treat algae on plants. To increase effectiveness, pause the filter during spot-dosing (just a minute or however long it takes you to spot-dose:) And don't forget to turn the filter back on! Avoid this method for treating algae on Mosses, Liverworts (Riccardia and Riccia etc.) and Vallisneria (Tape Grass).
If you have alot of areas to cover, you can exceed the 1ml per 10L limit. Spot-dose on affected areas, and perform a 50% water change after spot-dosing.