I have one aquentance from the UK (well met him at CZ and he was and may be still is a moderator of Water Fast forum here).. So he said to me that INternally we need to take it 12-15PPM max but higher strength ONLY Externally! Also he said that u need to swish (soory forgot the word coz I am not english speaking on the first place) it in ur mouth for 30 sec (or a min or even 2) and only after that swallow. Also some companies say it clearly that u could use it, say, for 10 days and then have a break..