algae issue

[Jarrett]

So i made a post a little while back about this green mat like algae on my sand bed. i want to say it is cyno but it isnt stringy it just clumps up my sand. i replaced one side of my sand bed and that side of the sand is pretty clean still but the other side is covered in this algae. i have a swc 150 bmk protein skimmer and i am running GFO along with weekly 15 gallon water changes. i dont want to resort to a chemical just yet. am i going to do any harm by taking out the other side of the sand bed and replacing it with new sand? the sand i originally had in their was from a 45 gallon reef that was established for 8 months and i stupidly used my old sand without rinsing it. their is also oxgyen bubbles all over my sand bed which i am assuming is from the algae is this normal.