The 20-foot long ground cord should be used to connect the meter to earth ground for most types of measurements -- especially if you are measuring near an ionizer. Make sure the wind guard (black plastic cover) is in place over the top slot in the meter, for most types of measurement. Switch both the POLARITY and MEASURE switches to the center position (the center is between "+" and "-" on one, and "STANDBY" on the other). Switch the RANGE knob to "19.99". Wait 10 to 15 seconds until the display is stable +/- 2 counts (+/- 0.02). Press and hold down the right switch to "RE-ZERO" for a second or longer. Then release that switch. Repeat this until the display reads between -0.02 and + 0.02 for at least 10 seconds after release. The meter is now at a proper "ZERO" and is ready to take measurements for at least 10 minutes before you will require another RE-ZERO step. If you change the knob to another range like "199.9", you will need to RE-ZERO again.

To measure, point the top slot (the one that is usually covered by the "wind guard") toward the ion source. At any time, you can change the POLARITY switch to + or -, to measure + or - ions, respectively. The display will immediately jump to a high value when you switch POLARITY, but it will settle to near zero in 10 to 15 seconds. Then turn the right-side switch to MEASURE. This will turn on the fan, and the display will read the correct number of thousands of ions per cubic centimeter in the air. For example, if the POLARITY is set to "-", and the display reads "-0.86", this is 860 negative ions/cm 3. If it reads -12.63, it means 12,630 negative ions/cm 3 (=12.63 kilo-ions/cm 3). When not measuring, leave the right switch on STANDBY to conserve battery power (STANDBY uses 1/8 the power of MEASURE). If when measuring near a strong source of ions, the display may go over-range; it will read a "1" at the far left with no other digits. Then switch the RANGE to a higher number, like 199.9 or 1999. You must do the RE-ZERO step again after a range switch. That is, set both toggle switches to center position, wait, and then set the right-side toggle to RE-ZERO and release. The less sensitive ranges 199.9 and 1999 will respond faster than the 19.99 range, which uses a slower filter.

Avoid measuring ions near charged plastic like synthetic fabric clothing. The excess charge will reduce both positive and negative ion counts in the region. Sometimes ions do not mix well in a room. There may be a cloud of negative ions in one area with almost no ions just a few inches away. Any fan (even a slow one) helps mix ions in a room. Without some mechanism for circulating the air, you may see the ion count go low, then high, then low, irregularly as a "cloud" of ions sloshes back and forth.

This meter reads exclusively the negative ions in the air when POLARITY is on "-", and positive on "+". Both ions can co-exist in the same volume of air, or there may be more of one than another.

If you see all three decimal points at the same time, the battery is low. Unscrew the back to replace it with a common 9 volt alkaline battery. Make sure that you put in the new battery so that the wire does not interfere with the motion of the fan.