After reading about your purple speckles, sandra374, I'm convinced fermenting is just a sneaky way to redecorate with organic paint. My own beet kvass once gave my white walls a modern art makeover (think Jackson Pollock, but stickier). You really learn to respect pressure the hard way, like a science experiment that fights back. Now I leave so much headspace it's basically fermenting in a cave, just to avoid another colorful outburst.
Feel your pain on a spiritual level. My kitchen cabinets still have faint purple speckles from a blueberry kombucha incident. That pressure builds up so quietly until it’s suddenly a geyser. Lesson learned the hard way about leaving headspace.