Demista Instruments
Compost Monitors

Composting Instruments

We believe that our simple and easy to use monitors represent the best combination of price and features available today.


Use the Model OT-21 Compost monitor to keep aerobic microbes active and decrease composting time, reduce odors, kill weed seeds, and reduce pathogens.
Not only will you save on the overall composting time, you will save time in taking measurements. You use only one instrument to take both oxygen and temperature measurements. 

The Model O-21 Oxygen Monitor is identical to the OT-21 except that it measures oxygen only.
You get results on a digital display and you get the results FAST!
  • Oxygen range of 0-99%.
    Temperature range of 0-199 deg. F(-18 to 100 deg C)
    Fast response time
    Long life oxygen cell(approx. 2 years)
    1/2"(12.7cm)high digital LCD display
    Low battery indicator
    Single 9 volt alkaline battery operation
    Rugged 3/8" diameter stainless steel probe
    Solid state temperature sensor at probe end
    Removeable filter probe tip
    Easy oxygen calibration
    Steel and aluminum monitor construction
    Laminated vinyl finish (not paint)
    Gold plated switch and probe contacts
    Weather resistant construction
    Monitor LxWxH= 6 1/2x 4 1/8x 1 1/2(165x105x38mm)
    Centigrade OR Fahrenheit temperature display
  • Probe lengths available: 3, 4, 5, or 6Ft (76, 102, 127 or 152 cm)