White sugar better for producing immune system stimulants. Too low a sugar content produces fewer active substances. Toxins bound by GA cannot be reabsorbed by the intestines or the urinary system GA is a building block for connective tissue, cartilage, stomach lining, vitreous humor of the eye and heparin. Antibiotic activity occurs on and after 7th or 8th day. The antibiotic component, usnic acid, can partly inactiveate viruses.
Mold is more likely to form where people smoke in the same room.
If mold does form, start with a new culture. Sediment is mostly pure yeast culture, good for speedy start of new batch. Kombucha produces its own preservatives - acetic acid, lactic acid, oxalic acid and alcohol. Periodically remove the bottom layer to rejuenate culture. Culture gets browner with use.