This is about two weeks worth. It gets thicker every week, but tnever get the fuzzy looking alage. I recently cleaned it off though.
I am using kessil H80 on the lowest setting, if I turn it up, the brown part (hotspot) in the middle gets bigger.
The hotspot is caused by 1 of 2 things or both. 1) the light is too close to the screen. 2) you are not putting enough flow over the screen.
Try increasing the flow and backing the light up about an inch or two and it should get better growth on the screen then. Flow should be just high enough not to shoot of the side of the screen.
So after moving my light about 4 inches away from the screen, and added more flow, this is what I got. What else am I doing wrong. LOL