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Old 20-04-2003, 06:15 AM
Mark Trueman
Posts: n/a
Default Question about CO2 levels in my tank

NjF wrote in message . ..
Since you were so helpful answering my last question, here is another
for the experts.

Before setting up the tank I tested tap water for pH, KH, and GH (7.8,
8dKH, 17dGH).

After running for a couple of weeks with injected CO2 pH remains
stable at 7.8 with KH and GH not changing as well. The co2 system is
Nutrafin's Natural Plant System which I purchased because I had read
several posts recommending them (or at least the bubble

As I understand it, co2 levels in the tank are directly related to pH
and KH. I don't know the algorithm, nor do I particularly care what
it is, but Chuck's planted aquarium page has a calculator that will
figure out the ppm of co2 based on the numbers you input for pH and
KH. Both his table and calculator give me a reading of about 3.8ppm
of co2 in the water, which is exactly where I started off before
adding co2.

The water is not being agitated in any real way as to cause the co2 to
escape. When leaving the end of the tube, the co2 bubbles are large,
but gradually decrease in size as they travel up the diffuser (I take
this as meaning the co2 is being dissolved). What do I need to do to
increase the levels of co2 in the water?

BTW, I get 1 bubble of co2 about every 3 seconds with about 4 bubbles
in the counter at any given time.

The tank is 10g with 15watts of light (will be upgraded shortly).

Any help is greatly appreciated. I have enjoyed reading many of your
posts already.


Did you test your tap water straight out of the tap or did you let it
outgass for 24 hours before testing the ph. I find that my tapwater's
pH rises after 24 hours from 7.4 to 8.4. I then inject co2 which
brings the ph back down to 7.4. What you might be seeing is tap water
with a high co2 level straight out of the tap. It would change if you
let it but your co2 injection keeps it the same.

Just a thought