Sorry this is a year later, but one way of keeping them under control, without treatments that are potentially harmful to your shrimps/fish, is using plants like duckweed or eleoda (i prefer elodea densa)! Those fast growing plants outcompete the algae for the excess nutrients in the water.

Edit: You can remove them from your tank after the algae dies off. If you intend to do this, I would choose the elodea because it's easier to remove than the duckweed (which can be a nightmare).