INEXPENSIVE co2 DISPENSER:
get yourself some 2 liter bottles...i like the dark tinted plastic arizona bottles.
Figure on one bottle per plant. In the bottles add 2 cups of sugar...then fill 3/4 way with pretty warm water...not hot.
Add 1/2 tsp of activated yeast...and shake it up like crazy...it will take a couple of hours for the yeast and sugar to start production of co2...for the first day or two , shake em up every couple of hours...but then once daily would be good.
Your plants don't need co2 at night, as they produce their own co2 during dark periods.
you can screw a hole in the caps of the bottles and get some aquarium tubing and silicone it to the top to get an air tight seal...then cut little holes all along the tube and put stoppers in the ends...
I wrap the tubes around the base of my plants. And have noticed a difference in growth since i started this method.
Good Luck