I use an R/O unit from Ron Harlan's Back to Nature Filtration. I have water from a domestic well so I have a pressure pump on the unit to provide increased and more consistent pressure. The following are the measurments taken with an electronic TDS meter Well water 160 ppm Product water 0 ppm Waste water 210 ppm Tom ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com. Search http://altavista.digital.com for "Apistogramma Mailing List Archives"!