High end carbon dioxide control system including tank and a regulator controlled by an electronic regulator.  The regulator enables coordination between CO2 release and the lighting cycle to ensure a constant supply of carbon dioxide only when the plants can use it.  Charge the tank and go - watch your plants grow.  Technical specifications and installation available at the reference link.  (This unit does not have a bubble counter.)

This regulator alone retails for $136.  Minimum set at $30.