I've been wanting to pick up a third 6.5 gallon carboy for a while, but I just didn't want to part with $42 plus tax for it. I found a used one advertised for $30. I talked him down to $20. After cleaning it, some white spots remain as shown. You can see the spots toward the bottom, under the water drops. I tried OneStep, dish soap and bleach, and CLR just in case it is calcium or lime stains. Nothing seems to be effective. I have noticed a flaw in this carboy. There seems to be a bubble in the glass. It has a date of 1973 on it. Would you be concerned with it?