The organic co2 suppliment works great check out the tank of the month from January I think it was the usersname is rivercats she uses the liquid co2 in that tank. Use excel if your gonna buy it from the store or you can buy a gallon of gluteraldehyde and mix it 1:1 with distilled water and store it in a light blocking bottle. Gluteraldehyde is the active ingredient in excel at 1.4% the glut I'm talking about is 2.6% and is much much much cheaper. But for your question. If pressurised co2 is 100% excel is ~70% at reccomended dosage 1ml/10g but can safely be dosed 2x reccomended. With average lighting. If your a master at plants you can dose 1.5ml per gallon of water bit ONLY if you know what you are doing.
