I heard that you can spray soda water on your plants

Nope, pretty useless. I forget the numbers but I do remember 8 good exhales is the same as 2 liters of seltzer water. Or something like that. Save your cash. If you want real benefit buy a real Co2 system, not a crappy yeast one either.

 

i suppose you COULD spray your plants with soda water, but will it do anything? probably not

 

Indeed good air circulation would help much more.

 

No, plants absorb Co2 through their stoma, not through their root system.

All that excess sugar is more likely to attract insects.

 

Hence him asking if spraying the leaves would work, Co2 and roots don't mix well.

 

You'd be better off having a Co2 burner.

 

Sounds dumb.