Very cool! Where did you get the calibration fluid?
-- Rob
PS. Do I hear TDS meter calibration party?
Mine is a 6 stage too... assuming you mean 3 prefilter stages, RO stage (4), DI stage (5), and a final 'taste' stage (6)...
I use stages 1,2,3,4,5 for my aquarium water and stages 1,2,3,4,6 for drinking water that is routed to my kitchen.
-- Rob
Dave, let me get back to you on my tap TDS... I make 200 gal a month for water changes, plus around 10-20 gal a month in the kitchen.
-- Rob