Dirty sandbed

[Northernseacorals]

You think there is a possibility the flow could be a touch low in that area?

Also could try to vacuum a test patch of the sand to see how quickly the colour comes back, if at all, I find testing this out will let you know if it's algae or something else, diatoms kinda grow in one direction favourably ( almost as if going somewhere ) algae will just grow every direction.