From the size of the grow container, I would guess that you could use house air it on earth is 300 ppm outside and much higher inside with humans on earth.
You will be looking at larger problems when they start to bloom. Ah she smell of a bud fillling up the house like a pot farm, (that hidden ?).
Working in a large grow area the ambiant co2 goes to 550-650 in a few minutes.
Save your money on the co2 tabs and use the intake fan with a filter on it.
The filter is required to keep out the Mighty MITE . How they find a pot plant is beyound me.
Its nice to have your own house or apartment, growing at home causes so much trouble. Build a biger chanber use one bathroom, get hids as the little florsents are worthless a tits on a bull.