A bit late but this problem might still be going on.
The dark green slime on the plants is blue green algae (Cyanobacter bacteria). It is a photosynthetic bacteria (a bacteria that photosynthesises like a plant). It loves nutrients, red light, low water movement and low oxygen levels.
You need to physically remove the stuff, cut back on nutrients, try to gravel clean the substrate (hard to do in a planted tank), increase water movement and aeration (this will mess up your CO2).
Drop the CO2 and fertiliser for a few weeks and do big daily water changes and try to suck the gunk out. When it has gone, then start adding fertiliser and CO2 back into the tank.
Maybe increase the blue light or check the light unit so you are getting a nice even colour from it. You want equaly parts red, blue, green and white light.
