Very good point. We had a culture going, but it went bad after a while. We'll get another one started right away. The freeze dried stuff was what we've used since before we had clams, and I like to think it worked well for us. It was something I always made sure we had on hand and could tell it was missing if we ran out. I'll keep using it until I get the better stuff. I guess after doing some reading, I think that Kent PhytoPlex Phytoplankton might be what I should be using. I certainly don't want to hurt my little guy. He's adorable.