There was a video posted on this site of a fellow using worm tea rather than fish. That is what got me started. "growies" appear in any aquatic system. You just have to account for them and make sure they don't stop the works.

I am sure your experiment will go well. The worm tea I am using is the natural drippings from my bins. I don't ferment it. I've recently been using it to root cuttings and ity works fine. I also see no scum or anthing else.