I don't disagree that the CO2 would quickly disperse but it would wash the leaves as it did, possibly magnifying the help to the plant.
My hope is to avoid another complex and expensive system which I need to maintain and just give my plants a little boost.
Look at this:
A CO2 Bio-system consists of a container, such as a 2-liter soda bottle, with small amounts of yeast, sugar, pH-buffer, and water. These ingredients naturally ferment to produce CO2. The container has a stopper with a hole through it for a piece of stiff plastic tubing that attaches to a piece of flexible tubing, which dangles into the aquarium and allows the CO2 to bubble into the water. The CO2 in the bubbles dissolves into the water, increasing the the concentration of CO2 and the growth of the plants. This is a very low-tech, natural, and inexpensive way to add CO2 to aquarium water.
I would simply hose down to the plant, add a tee and two pieces of weighted bubble wand and change the ingredients once a month.
And give my granddaughter a science lesson at the same time :-)