View Full Version : I thought CO2 was supposed to lower ph.
NJ Devils Fan
04-17-2003, 10:11 PM
I have had my CO2 working great for about 3 weeks. The ph hasn't lowered at all. Why is this? I want it to lower because it's around 7.4 or so and I have mostly tetras in the tank so I want it to be around 6.7-6.8.
Also, If I did want to lower my ph with peat in the filters, what kind do I use? Is peat moss the same as peat? Do I look for anything special.
ChilDawg
04-17-2003, 10:14 PM
CO2 is only a weak acid when dissolved in water...it is more likely that the pH would affect the solubility of the CO2 than the CO2 affect the pH, especially with well-buffered water. What are your GH and KH values?
NJ Devils Fan
04-17-2003, 10:20 PM
From when I tested about a week or so ago, the gh was 7 and the kh was 4.
ChilDawg
04-17-2003, 10:26 PM
Hmm...how much CO2 are you adding? It would seem like those numbers aren't really good for buffering.
By the by, peat moss is what a lot of people use in aquaria...but make sure that it is chemical-free. I'd suggest just going with stuff that you buy at your LFS or from Big Al's.
CO2 is an extremely soluble gas, and any significant amount disolved should lower the pH.
For the pH/KH/CO2 tables, see:
http://www.thekrib.com/Plants/CO2/kh-ph-co2-chart.html
ChilDawg
04-17-2003, 10:43 PM
*Yells at his now-sleeping chem. major roomie*
Panic
04-17-2003, 11:45 PM
What sort of reactor are you using? Seems like you may not be dissolving as much CO2 as you might expect and that would explain the lack of pH shift.
NJ Devils Fan
04-18-2003, 9:46 AM
I have it comming through a good air stone and then going through the Hagen CO2 bubble counter (the zig zag thing). I don't have a CO2 test kit, but if I see one at my LFS, I will pick it up.
NJ Devils Fan
04-18-2003, 9:56 AM
Oh yea, should I boil the peat before adding it to the filters?
Sumpin'fishy
04-18-2003, 11:14 AM
If you have a pH and KH test kit....you are fine. Measure each one right now and then take those figures to: http://www.csd.net/~cgadd/aqua/art_plant_co2chart.htm
Fill in the two numbers and you will get a pretty exact CO2 concentration. You can also print out the page and use the chart at the bottom for general figures. I'm pretty sure you aren't getting enough diffused for your liking.
I've never used peat, but I've read to boil it 5 to 10 minutes prior to use.
NJ Devils Fan
04-18-2003, 1:26 PM
WOW, I just checked my ph and it was 7. I haden't checked it in a few weeks. I guess that diffuser really is worken then. My kh is 4 and the CO2 is 12 ppm. Thanks for that table Sumpin, its very good.
Sumpin'fishy
04-18-2003, 3:13 PM
Chuck's whole website is pretty good, IMO. Glad to help!
thalassic park
04-22-2003, 10:14 AM
Hi,
I believe between pH 7.0 - 4.5 the CO2 creates carbonates & lower than pH 4.5, carbonic acid is created.
http://www.tomgriffin.com/aquasource/hardwater.shtml
HTH