What was your hardest algae to remove from your tank?

I had a string algae in a planted tank that I just could not get rid of. Ultimately, I resigned to keeping the tank light off and it slowly died back over a few weeks. I'm afraid to put the light back on, but there are a couple live plants in there that would like it.

Algae bloom or green water is the most difficult that I have encountered because they practically turn your tank water to green color since it doesn't grown on the surface but suspends in the water.

Algae blooms are really difficult to get rid of that's when I started to clean my tank with bleach water.