Quote Originally Posted by BoomBoom82
if u no ur tap water is 7 use that 2 calibrate u tester an calibrate 2 7! lol
Don't listen to this advice.

The buffers (calibration fluid) are reusable for quite a while as lo0ng as they do not get cross-contaminated. Keep them tightly covered between uses.

Tap water does not have the correct ionic strength to give a reliable calibration, and you have no guarantee that it is not going to fluctuate ever.

Don't let your probe dry out entirely. Some probes I think you CAN let them dry out, but if yours came with a little rubber condom thing to protect it, and it has a bit of cotton wool in the tip, keep that moist and keep the probe in there.

If your probe gets cruddy wih organic buildup, you actually can use acetone to VERY gently clean it. Rinse well.