Honestly GL I don't know anything about C02 except the very VERY basics such as don't breathe a bunch of it in and it can KICK ASS on your yield if used right.
That's my honest limit right there.

GL I've only done the Botanicare nutes and never tried the GH 3 part. Quite frankly I don't understand the whole 8ml/ thing and never have. I'm not saying they're bad or anything only that I know 0 about them in general. I have several friends who use them with good results but that's about all I can tell you.

Sorry I'm not more help.....but if something happens that I can help I'll pipe up.