Hit inputs, scroll down to highlight your SL1 and hit enter. Scroll down to highlight ph, hit enter. Highlight calibrate, hit enter. Place the probe in ph10.00 solution. Wait for the "raw" data number to slow down and remain steady between 4 or 5 numbers. Hit enter and repeat the process with the probe in the ph7.00 solution. When you hit enter, it will save. Back out until you get back to the home screen. You're done.
*** Make sure you update the SL1 firmware to v1.12. You can get it at http://forum.digitalaquatics.com