From: "gooch" Sent: Tuesday, November 28, 2000 8:56 AM > If I get this right then if I measure 250ppm then the water > in us would be (.75) 333 us?? Close enough for "government work", as they say. My own local water runs about 140 ppm GH and 185 µS, which is just about dead- on to 0.75. The differences, as I pointed out before, lie in the fact that TDS also measures things that aren't _literally_ dissolved in the water (ionized or otherwise), but also includes silts and other turbidity components that are simply just fine enough to remain in suspension... -Y- ------------------------------------------------------------------------- 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"!