Mystery Green Water Die Off

I had to strip my 50 gallon heavily planted tank down about a month ago. Ever since refilling the tank, it's been almost completely saturated with a pea soup of green algae. I didn't really do anything about it because I thought that I'd just have to wait for the plants to grow in again. Up until tomorrow, it was as thick as ever.

Yesterday, I brought one bunch of cabomba and 20 ghost shrimp home and into my tank. Yeah I know, I'm bad for not acclimating, but their tank sure looked better than mine. Last night when I turned the lights off, I could barely see 1/4 of the way through the 12" wide tank. This morning I can see clearly to the back of the tank, though the water is still cloudy with green algae. It looks as if I did a 50% water change. As I see it, one of there things could have happened:

1) The new additions to the tank were a complete coincidence. The green algae was already slated to start collapsing last night.

2) The cobomba out-competed the algae for nutrients. Just one bunch. In 8 hours. At night. Huh.

3) Ghost shrimp eat green water algae and no one has ever noticed this before.

4) Cabomba releases an allelopathic chemical which inhibits the growth of green water algae. If the cabomba is responsible, then this would explain how it could have had an effect over a period of time with no light.

All of these seem pretty unlikely to me. Tell me what you guys think.