Mordachai
Aquarium Advice Regular
Sorry about the image quality - phone camera.
Basically, it's the white - clear stuff clinging to that leaf - reminds me a lot of a spider's web. whispy, whitish/clear material.
I've probably got some small colonies of a cyanobacteria, definitely some algae.
My tests are 0 ammonia, 0 nitrite, 20-40 ppm nitrate, low-light conditions (2x 6700k T5 NO).