Ive noted in my article that you could use airstones but it is a very poor method so id recommend otherwise. As for the C02 seperation unit i used a 20oz bottle and ran the line from the C02 bottle down a few inches and the tube to the tank high in the bottle. Ive had no results at all with this and the residue still collected in the tank. I didnt use water in the unit so maybe thats the problem, any ideas why it didnt work? Since then i havent used the seperator unit because it hasnt worked the way i set it up.