Co2 how2

I know co2 is important and it helps cool the room and can almost double growth rates but I you don't the couple bucks it costs for a co2 unit and u were gonna do the dry ice thing how do you know how much is enough? Is too much a bad thing?(I'm sure it is as with almost every aspect of growing,besides love) what are if any signs of co2 poisoning? My method would be a cooler filled with dry ice some holes drilled in it and tubes running out to the room and hit with a splash of warm water when u need a dose of co2. Would this work? 4x4x8 l w h

probably but that dry ice melts pretty quick and i dont think u want to fill a whole cooler full of it at once..i just put a pound of dry ice in two different cooking pots (2pounds all together) then get a piece of cardboard or paper and cut little squares all over so it leaks out slower..then i put a weak lil fan next to it to blow it all on or towards my plants..melts in a couple hours or so and i do this everyday or everyother day