Oh yeah, I also picked up a Milwaukee SM802 SMART pH/EC/TDS Combined Meter/Tester from eBay ($148.99 w/ shipping) and it was delivered yesterday. I spent some time taking different readings:

Kitchen tap water (KTW):
PPM - 400
PH - 8.0

1 Gal KTW w/ 2 tea nutes:
PPM - 900
PH - 6.6

1 GAL KTW w/ 2 tea nutes & 1 tea PH down (waayyy to much PH down):
PPM - 1050
PH - 3.7

1 GAL KTW w/ 2 tea nutes & 1/4 tea PH down (bingo mixture):
PPM - 840 (I might have put less than 2 tea of nutes)
PH - 6.3

Grow tank
PPM - 1430
PH - 6.2

I must say, you definitely need a meter if you're going to be serious about hydro :weedpoke: