Weird bubbles on tank surface and green algae on rock

[Bilolos]

Hello fellow reefers,

As tittle says my tank has some bubbles only on surface and green algae on rock. Any idea what cause it?
Tank is 6 month old 140g sump included started with dry rock and live.
For filtration I use Reefmat 1200, Oxydator 12% (A) with 1 catalyst and skimmer.
Feeding 2/3 per day frozen and 1 nori every other day.
Water change every week 10%.
Salinity 1.024
No3 20
Ph 0,11
Alk 8,4
Magn 1290
Calcium 420

Your help is greatly appreciated.

 

[Timfish]

For some reason your overflow isn't skimming the surface. The water level inside the overflow should be an inch or more lower than the water level in the tank.