Hey Txc,Have you got all the light leaks in your cab fixed.If you use co2 it is heavy than air and will settle on the floor.Set it up above the plants so it will drift down around your plants.I wouldnt start using co2 till they are 4" tall.You dont have to put water on the dry ice.Just open the contrianer with the lights on and cover it when light out.It will evaporate in the air all by it's self. PEACE