Id

[Chiefmaster30]

Anyone know what this could be? It started around a rock I had with a favites Coral on it. I siphoned the sand last week and now it has spread all over everywhere I siphoned. Tank is 120 gallon dt with 30 gallon sump. 2 yrs old! Params are:
Salinity1.024 refractometer
Ammonia 0 Api
Nitrites 0 API
Nitrates 2ppm Red Sea
Phosphates 0.03 Salifert
Alk 10.5 Red Sea
Cal 450 Red Sea
Magnesium 1350 Red Sea
Only thing I dose is brs

2 part but recently stopped dosing nopox about 2 weeks ago.

 

[DSC reef]

Blue green cyano

 

[Chiefmaster30]

Ok! Thank you! Must’ve been triggered by stopping the nopox.