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Re: Trouble with CO2

> Date: Thu, 03 Jan 2002 19:30:31 -0500
> From: John Russo Jr <jr at medcomres_com>
> A few weeks ago I asked members of this group for advice on raising the KH
> and using CO2 injection to adjust the pH of my freshwater tank (KH =1).

> When I raised the KH to 3 and turned up the CO2 the fish showed extreme
> O2 deprivation get the pH to less than 7.4.

The increase in KH alone won't affect fish at all, except for the increase
in pH. In general, fish are insensitive to KH.

> Seriously, should I be surprised that the fish couldn't breath at a KH of
> and a pH of 7.4 up to 8?

Yes, you should be very surprised. A KH of 3 and pH of 7.4 to 8 indicates
CO2 levels of 4.5 down to 1 mg/l - not much higher than you would find in a
non-injected tank. I would look elsewhere for your souce of breathing
problems.  Do you have good water circulation? Are your test kits returning
valid measurements (it doesn't seem like they are)?

> Also, sometimes I get the
> impression that the recommendations I read on this site (and elsewhere)
> refer to plants but are not good for fish, particularly discus. Is this
> balancing act between keeping discus and growing plants more difficult
> with other fish?

Discus should be perfectly fine at a KH of 5 or less and pH of 7.0 (15 mg/l
CO2 or less). You might want to review my "Discus in Planted Aquariums"
article on my web site.

George Booth in Ft. Collins, CO (gbooth at frii dot com)
  The website for Aquatic Gardeners by Aquatic Gardeners
    New updates in Dec '01! Discus article, new links, large photos
      http://aquaticconcepts.thekrib.com (mirror)