sorry for my english i'm a french spoken person...
i find your projet very nice and i'm doing one. i start my projet 1 week ago.
but i find something that maybe great for you too. is the nano co2..
here the link:
http://www.plantedtank.net/forums/diy/27883-nano-co2-ada-style-regulator.html?posted=1#post239680
it cost a bit but for the place and time is very great... no mix and take less thand 5 min. to change the co2 recipient whit a full one...
