Great to see thick growth!
Couple things. The round holes in the earlier pics are pods... are you sure it did not go past 7 days?
Also, did you rough up the screen?
I see what you are doing in your harvesting... you are only removing the longs strands. Instead, do this: Use your fingers (not fingernails) to push off most of the algae. The rougher the screen, the more algae will remain.