Yeah thats where I got my PH unit, but less than a month and a half in and it went wacky(uncalibrable). Not that its Anthony's fault, but just dont feel like waiting for the mail and someone might have a slightly used one.
you buy these pouches that contain liquid w. a perfectly set PH (sell them in PH of 4,7,10) and your probe will bounce slightly(if its not dead), and w/ a mini screwdriver you calibrate it w. the probe inside the PH pouches to the proscribed PH. you do this with 2 pouches (I do pH 7 & 10) and go back and forth 3 times and adjust accordingly to each pouch's PH
here's a link to a good article by RHF. it covers recommended calibration solutions, how to double check your solutions using household borax and the calibration process itself. http://www.reefkeeping.com/issues/2005-02/rhf/index.php