Hello, Thanks to everyone who helped me set up my planted tank, firstly...Lotus, Iggy, Ballon Fish etc! (Ballon Fish you're journal has really helped me know what to look for as far as growth speed!) I've been told to turn off my DIY Co2 at night and plug in the airstone (which runs on a timer oppsite the light.) I need to cure some silicon on my Co2 system to make the seal airtight today, so assuming a 24 hr. cure time, I should have it in the tank by tomorrow. I'm using a bell diffuser for now that I made, but may just buy a real diffuser. I'm not sure how to turn off the Co2 at night. Do I just, take it out of the tank? Is it that simple? Will 1 3L bottle of yeast mix still last about 2 weeks? Also, what if I go away for the weekend and leave it "on"? I'm assuming if my KH is stable, my pH will be too, and that if I'm not pumping dramatically more than 30ppm Co2 into the tank, my fish shouldn't be harmed. Its a 38G with a compact flouresent 96W, 6700K bulb, flourite, wisteria, hornwort, and errr...something else that grows fast that the LFS guy who has a co2 planted reccomended. Its been dosed with SeaChems Flourish for Micros, Iron, and Excel until my Co2 system is sealed and running. Will pick up Fleet Enima and Green Stump Remover for macros today assuming I can find them! Thanks for putting up with all my newbie planted tank questions everyone! I really really appreciate it! And so do my 5 tetras who are going to move there in a month, and so do the lucky ottos who are going to have some algae feasting to do until I figure out my fert levels for tank! *BOUNCINGS -Christina EDIT: According to one or two threads that came up on the search feature, a lot of people don't turn theirs off. Should I just measure the ph and kh with lights on, again with lights out, and then again when the lights first come on, to see what kind of Co2 levels I'm looking at? I won't have inhabitants until the plants start to grow, nitrogen is absorbed and I get the peaks of cycle out of the way, so I can't use the "gasp" test!