Do you have a loved one who has a greenhouse?

**Johnson CO2 Generator
Fertilizes greenhouse air - easy and inexpensive to install**

"The Johnson CO2 Generator automatically provides the carbon dioxide to meet maximum growing potentials - and operates for only pennies a day. The Johnson Generator can easily be installed in any greenhouse. No expensive ductwork is necessary and CO2 is diffused evenly without supplemental fans."
...
"Nighttime levels in a greenhouse range from 400 to 500 ppm due to plant respiration. Shortly after sunrise this level will drop to normal atmosphere (300 ppm) due to the plant using the early light to start photosynthesis. After 3 to 4 hours of early morning sunlight the CO2 level can drop to around l00 to 150 ppm, then growth is practically stopped. Supplemental CO2 added during this period can substantially increase your plant and flower production."
http://www.johnsongas.com/industrial/CO2Gen.asp

Linked from http://timblair.net/