Well, real world vs. manufactuers numbers will realistically put you at between 12-15, not 4-6. Even 10ppm would be great as you'll get about 680 gallons of 0 tds water from you DI cartridge.
Rob Reef Keeper, do you have a link to where you purchased this Hi S membrane?
Take care - Howdy
It's not 6800 gallons, it 6800 total ppm of TDS absorbed per a 1 pound mixed bed DI resin cartridge.
May have been a mis- type on your part, but didn't want people trying to get 6800 gallons out of one! :)
And to the OP, what is real important to know is the rejection rate of the membrane...
