Quote Originally Posted by Opie Yutts
I have an inexpensive Control Wizard for both PPM and PH (two pens). As far as I know they've never done me wrong.
I should have knocked on wood. My PPM meter started sucking. When I add nutes the ppm goes down. I got a little nute burn last feeding and now I know why. I thought it was kind of acting weird when I was mixing that batch, and come to think of it, when I was calibrating it about 3 weeks ago. I changed batteries then too.

I'm leaning toward the truncheon, which is just a style of meter according to the guy in the hydro store. As far as I can tell Bluelab makes the best of these, or at least the most popular. Maybe even their combo meter. It has a lot of things I like about it, especially the 5 year guarantee.
Bluelab : Manufacturers of the World's favorite pH, EC, CF and ppm handheld meters and controllers

Those individual meters are huge though. I'm thinking they are for pools and not small reservoirs. The lights are cool though.