Hmmm...5 hours of light time seems like it wouldn't start or fuel algae. How many watts is your lighting?
You mentioned that your ammonia and nitrites are 0, which is great! What about your nitrates? High nitrates (and I'm not real sure how high; I'll just say 60
ppm) could contribute to the algae bloom. Nitrates should ideally be kept in the 20-40
ppm range.
Your shrimp will pick around the bottom of the tank for uneated food. Usually there will be enough for him at the bottom to find. You don't need to dump more in just for him.
If, though, you see him swimming around "restlessly" you can drop a flake or two his way. Also, you can feed him algae wafers. These will not contribute to the algae in your tank. (that is, if you don't overfeed them!) I used to spot-feed my shrimp. I had a long pair of tweezers and I put the wafer right in front of him. I did it this way because my betta would get so curious about the wafer that he wouldn't let the shrimp eat in peace. If the betta didn't see the wafer, then he didn't bother the shrimp! I would feed about a quarter of an algae wafer 2 or 3 times a week.
Once a day feeding is best. I would probably feed once a day until you get this algae under control.
Another thing I though of: Are you doing gravel vacs when you do water changes? Vaccuuming the gravel can help to pull excess wastes and food from the gravel. I vac half of my tank one week, and the other half the next week. That way, I'm not disturbing too much of the good cycling bacteria, even though most of the bacteria is in my filter media.