[Pumilo]

Whatever are you talking about? Green Yeast? I've never heard of such a thing. Regular active bakers yeast can be purchased at any grocery store if you want yeast to sprinkle on top of your cultures. Regular Brewers yeast can be purchased at any health store, or at Josh's frogs, if you are looking for yeast to mix into a homemade FF media.

 

[Pumilo]

Hey John, how about a complete breakdown of the recipe you are using? We could be much more helpful with a recipe. I'm guessing Tony is right and you have some Spirolina. Is it a very, very dark green powder?

 

[Pumilo]

Sounds like a basic Carolina mix. I think it's a bit low on potato, though. Typical ratios are more like this:
6 cups potato flakes
1 cup powdered sugar
1 to 2 cups brewers yeast
So that would put your recipe about a cup low on potato. That means you have too much sugar. And yes, I would change back to a tried and true yeast.
Here is a thread discussing Carolina ratios. http://www.dendroboard.com/forum/food-feeding/67563-ff-culture-media.html
Josh's Frogs sell 5 lbs of brewers yeast for $11.99 or 50 lbs for $74.99.
Hope it helps.