Is this gha, turf, or something else?

[Mike T IL]

Please help identify. I manually remove and it comes back in a week. Alk 8.5, calc 480, mg 1380, PO4 .05, nitrates 10.2, salinity 1.026, Tmp 78. 5 gallon daily auto water changes. Also have turned off the lights for a period of 3 days a few times.

 

[Lavey29]

Looks like GHA. How old is your tank?

 

[Mike T IL]

2 years