Black Mollies and Algae

I have 3 black mollies in a 50gal planted tank.

At first they were like lawnmowers in eating any green hair algae.
But now they are mostly surface skimming and ignoring growing green
hair algae. (at least the surace is nice and clean!)

I only feed once everyother day and then just a small pinch that is
eaten in less than a minute..

Any advice?
I do have a few Amano shrimps, not enough to make any difference.
I can also find true SAE at my LFS, but haven't added any to the tank.

Tank is about about 5 weeks old, 200watts CF lights.
Just got my pressured CO2 set-up.
30-40% water change every week.
Canister filter

thanks,
steve