I had this filamentous algae before. Never managed to beat it but I saw a difference when I decreased light intensity. Tom Bar suggested that it was due to low biomass which was true in my case but I think in your case its more about low CO2 and high Lights. Since you have fauna in there I would not suggest you increase the CO2 or at least increase it slowly always observing fish behavior. I would also add liquid carbon (Easycarbo or Excel) in overdose (x3 or x4 suggested dose), just ensure you have no shrimp in there. You have your lights at 50% now which is good but since I don't know much about the ADA lights I would even go down to 40%. All you need is some healthy growth and when this happens you can stop dosing the liquid carbon. Have in mind the liquid carbon will kill off all of the algae when overdosed however if you stop it, the algae will come back if the root problem was not fixed. Also don't cut of the liquid carbon immediately, go from 1 week of x4 overdose to 1 week of x3 overdose and so forth until you stop adding it.
This is MHO:
Lower light
Increase CO2
Siphon all algae
Overdose liquid carbon
What kind of substrate do you have?
Thanks