anyone use a sprite tds meter to test water quality? if so, what kind of readings do you get? i'm having a hard time getting consistent readings. i believe my ro/di water is coming in at about 003-006 ppm. is that .003-.006 or is it 3-6? i don't get the zero thing. also, i get a flat 1 when testing other water sources. it comes right in at 1 which seems strange to me. i picked it up used so i dont know age of batteries but the manual says batteries are out when the monitor fades in and out not when strange readings come on. anyway, some help with this meter would be awesome. tanks in advance!