what algae is this?

[dmjr1201]

I was sitting here looking at my tank and noticed bubbles coming up from the sand. What could this be ?
There a small brown patch and has tiny bubbles on it. Sand is about 3 weeks old. Could this be my problem.
Any helpful advice is greatly appreciated.

I have a 120 48x24x24
Temp 78
Salinity 1.025
Phosphates 0
Alk 8.9
Calcium 420
Nitrates 2
All salifert tested
OR T247 x 2 - 8hrs (blues only)
T5 retro 48" x 2 4hrs

 

[dmjr1201]

Also rocks are new but from an established tank at my LFS .

 

[Reefing Madness]

Yikes.
Dinos
How I beat dinoflagellates, and the lessons I learned ? Advanced Aquarist | Aquarist Magazine and Blog
Problem Dinoflagellates and pH by Randy Holmes-Farley - Reefkeeping.com

 

[dmjr1201]

Thanks for the links Reefing Madness! Just checked the tank out and the same spot from the picture is almost white again bubbles gone. I have 2 more hours of light, keeping an eye on it to see if it gets darker and bubbles again.