ec meter

hi everyone
i wish to buy an ec meter so i can monitor the nutrients that i will be giving better.
the only problem is i don't know how to use this gadget and what brand i should get.
didn't want to spend much but then again i don't want a crappy one witch doesn't gibe me accurate readings.
anyone can help me out ??

thanks loveweed

I have an Oakton TDS low (http://www.hydrofarm.com/pb_detail.php?itemid=10951) though I only paid $70ish for it. It's waterproof and reliable. It reads on the 442 scale or .7 conversion and it's easy to calibrate.