if i may, co2 is not oxygen, co2 is carbon dioxide. although technically part oxygen, carbon dioxide is a by product of the plants metabolism, when introduced into a nutrient solution, its actually polluting it. kind of like feeding it it's own excretions. tabs should be dissolved in water, close to your grow, not IN your grow solution. for me seltzer waters cheap, just unscrew the bottle and let it sit out in the grow room and let air flow do the rest. in basic terms, you want the co2 flowing at the top, not the bottom. weedss, just get through that first grow, learn the basics, and you can fine tune things later when you're the Tony Montana of the far east.