Hi SqueakyClean,

Use your best judgment... I have had both happen to me. If the indoor temperature is cool, say 70 or so, the 2.5 - 3 week old tea should be ok. It would depend on how you prefer the tea though sweet-vinegar.

The black tea, hard to say without seeing it. I have had a dark grayish or bluish type of film around the culture on my greens and still used it as I did not believe it to be mold; so here, use your judgment.

grz

Mold can grow on your kombucha, and there are some things you can do to prevent it - make sure everything you use is sterile, the jar especially. When you make the tea, cover it while it cools so that no mold can get in, then poor it in your jar putting the mushroom in with clean hands. Always cover your jar! I've used paper towels, clean cloth or coffee filters and then a rubberband. Starting your batch with a little of last times batch will help to keep mold from having a chance or you can put a little bit of vinegar on top of the forming mushroom to kill the mold.