My roommate is a landscaper and was able to "borrow" this pH meter for me. Anybody have any experience with these. I was able to download a .pdf instruction manual from www.specmeters.com. but now and then I get inconsistent readings. Wondering if I need to replace kci dispenser or chip, and how to tell if I do need to. It retails $140-$170 so I figure it's gotta be good. Also I just replaced batteries cause they where DEAD when he snagged it for me.