# CO2 by day. O2 by night? and pH?



## fishyfish (Jan 18, 2010)

totally newbie here. I've had a 3g nano up and running for about 5 months. I'm finally catching up with the reading, these forums and books, I should have done 5 months ago. I'm excited to redo my hardscape and plants now that I know a little more. I have the CO2 advanced system from ada that I want to hook-up for the first time. I understand I should run it a little before the lights come on and shut it down a little before the lights go off. does using CO2 by day, mean I really should be pumping some O2 in at night? I haven't been doing either. also, someone mentioned the pH is likely to drop using CO2 ... is this true? my pH has been in the 6.0 to 6.5 range. and my KH is so low, around 1 or 2dH. GH around 8 or 9, all fairly consistent. no ammonia, no nitrites and moderate nitrates less than 12.5. should I use an alkaline regulator when I hook up the CO2? thanks.


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## Msapp1 (Feb 11, 2010)

I've got a 10 gal nano set up, when i put my DIY CO2 my pH dropped pretty substaintially. I also run it night and day, no fish deaths.


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## Msapp1 (Feb 11, 2010)

I also don't aerate, at all. And the only water disturbance is just below the surface to prevent gunk build up.


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## flashbang009 (Aug 6, 2009)

The ph will drop, and a low kh i believe will cause more drastic drops. Observe your fish at night. If they gasp at the surface, then an airstone is a good idea. I recently added an airstone to my 75 gallon that has co2, and the airstone is on a timer at night, and turns off an hour before the lights come on. This way the CO2 has a chance to build back up before the lights turn on. The airstone helps with fish health as well as water quality i've noticed


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## fishyfish (Jan 18, 2010)

Thanks flashbang. I guess I was hoping for someone to confirm this. From the little I read and understan, seems like it could only help the plants and fish to add the O2 at night. I'll add a small aerator on a timer and also figure out if I need to up a dosage of nutrients or an alkaline buffer to maintain a reasonable KH.


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## flashbang009 (Aug 6, 2009)

Sounds like a good plan. I still don't understand the whole ph kh relationship, but you can look on the internet for info on that.


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## fishyfish (Jan 18, 2010)

I came across this conversational analysis of the CO2/02 relationship in the aquarium on The Krib. Seems to cover it all with convincing authority. http://www.thekrib.com/Plants/CO2/night.html . Based on this I'll find the proper CO2 rate for my tank with, fish and plants, and just leave it going 24 hrs a day. Supposedly this would maintain a less dramatic pH shift (less so than CO2 on by day and off at night) and should have no major effect on fish health as long as I don't overdose with CO2. In other words CO2 concentration and O2 concentration in water (our aquariums) are, in practical application, unrelated.


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