sandbed/algae/nano issues - take your pick.

[rsisvixen]

I would take a stab at the bright green being a form of cynobacteria ( cyno can come in a variety of colours not just red. ) Its not an algae per se but a bacteria that also requires photosynthesis to survive. Usually its a high nutrient indicator, nitrates and phosphates.

The other stuff sounds more like diatoms usually an indicator of high silicates and pretty normal for a tank still cycling.

Most systems take a while to reach equilibrium even if they've cycled.