Thank you for your input. From what you described, the high pitch noise that the EXT120 makes appears to be quite annoying. How bad is it really? If I use the unit to produce ozonated olive oil 24 hr a day, this could be a problem, since I live in a small apartment unit.
How is the overall construction of the unit? I was told that the "cold corona" that the EXT120 uses is not really "cold"; it still requires a fan to cool it down. Is that true?