Today I found some purple crystals on the bottom of a jug of pyment (made with store bought grape juice and orange blossom honey), which is clearing. The jug is in the cellar, which is slightly colder than room temperature, probably 10-150 C. I assume these crystals are "wine crystals" (potassium bitartrate). I'm under the impression that they're harmless. Is this so? Should I rack?