In order for the thing to be even close it needs to have lots of air flow in the room , from the floor up. As co2 falls the meter reciever must be located mid room about thickes part of the blooms. Now thick air cooler will have a different reading cause the air is thicker.
Normal out side is around ?450 ? If the room is well sealed if you do not breath it can be around 1400, thats a 13 x12 x 8 ft.
Also what is the humidity in the room , that may be one more factor.
NOTE check the span on the meter and make sure conection are clean.
Look into getting a Dataq usb to read the output over the total cycle. They are about 50 bucks, and are well worth it. Use some speaker wire to get your reading.
oldsanclem Reviewed by oldsanclem on . CAP PPM-3 problems I recently got a ppm-3 and immediately noticed that it was not always shutting off the solenoid valve on my co2 tank after the relay point (1600 ppm) had been reached. It just kept going up until about 4,500 ppm until i noticed and restarted it. It goes for about 3-5 hours of correctly shutting off the valve and then eventually it will glitch and keep the valve open. now i have a seperate issue. originally the co2 ppm in my room was 900 at base level. outside on my lawn between trees Rating: 5