What's the easiest way to cultivate algae?

I have Ghost Shrimp and that's one of their main food sources. Two of them are pregnant though, so I want to make sure that I have enough food to go around when the eggs hatch.
I have some tank water in a see-through plastic container with a lid on my windowsill... But, It seems like a very slow process.
I have algae wafers but, my wafers have copper in them and copper (from my previous experience) kills shrimp. I also have freeze-dried bloodworms that are a non-copper food. I was told that they would gorge themselves on the worms, though... I don't want them to die.