Looks a lot like Spirogyra.. This might help:
Description: Fine strands of green algae sometimes very long in length. Slimy to the touch. Under a microscope the chloroplasts are aligned in a spiral - hence the name.
Cause: Often appears a couple of weeks after a disturbance that causes a spike in ammonia. This can be anything from a disturbance of the substrate to a dead fish gone unnoticed. Likes high light levels and high nutrient levels.
Removal: Once it has appeared it can be very hard to clear as it thrives in the same conditions as plants. Pick out as much as possible and do a three day blackout with CO2 turned off and doing large daily water changes. Dose back with macros after the water change. Afterwards I found normal dosing Excel also helped, you could use EasyCarbo or TNC Carbon also. Rosy barbs will eat it if made hungry. Also try reducing the lighting.
Another method to try is to try lean dosing at around 1/4 to 1/8 Estimative Index levels for a few weeks. I had good success doing this.