HELP: Gunk Attack on Gravel

[Mr. Breeze]

I set up a planted Evolve 8 two months ago for my grandson. This is a planted tank with Java Fern, Wisteria, Australian Bacopa, Tiger Lotus, Dwarf Sag. and Pond Cabbage. Fish currently are 9 Neons, 2 Red Dwarf Gourami and 2 Panda Corys and 4 Ottos. Fish are well and plants seem to be doing fine.

I am dosing:

Excel (No injected CO2)
Flourish
Stress-zyme

I have added to the filter:

Chemi-Pure Elite bag
BioMax bag for additional bacteria health

My son in-law sent me a photo of this gunk covering the gravel in the back of the aquarium. Something is not in balance here. Any ideas what this is and any corrective action. Are the algae tabs not being eaten?

Thanks for you thoughts here!

Mr Breeze

 

[mohican]

Looks like maybe over feeding or over fertilizing. Hard to tell from the pic, its kinda blurry.

 

[snoopy65]

It looks like cyanobacteria. Check here Causes and Cures for Cyanobacteria, also known as Blue-Green Algae or Slime Algae