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Re: Too much CO2?

To my original post, Dennis replied:

>Ron also mentioned in his post that his water was 14dKH.  
>My thoughts are perhaps that Ron does not have an actual 165 ppm of CO2.
>There could be other chemicals acting in the water which could be effecting
>pH reading as well as the CO2.  It is my understanding that CO2 levels above
>30ppm do not help the plants any more, and that at levels over 40ppm few 
>fish can survive. 

I'm assuming the change in pH is being effected by the CO2 I'm adding and
not some other chemical, since the water I'm starting with is pH 8.2, 14
dKH, calculated to have about 3 ppm CO2, or about what I'm lead to believe
is a normal equalibrium content for CO2.
The observation that "at levels over 40ppm few fish can survive" is basis of
my concern. Adding the CO2 from a 2 liter yeast generator brings my pH down
to about 6.6 which based on dKH of 14, leaves me with CO2 at 165 ppm, hence
my reluctance to add fish.

>My case I have natural water at 27dKH and 8.4 pH.  With really injecting the
>CO2 into my tank (only 55 gallons) I can only get it down to about 7.8pH.

Just curious Dennis, but what kind of fish are you keeping in this water? 

 >However if the CO2 is actually that high perhaps an air stone or two added
>with normal air would help decrease the CO2 level.  The other option would be
>to reduce the flow of CO2 with a better valve.

I was under the impression that putting any sort of restricting valve on a
yeast generator was asking for a disaster. I suppose you could do this if
the extra CO2 was "bled off", but this seems like something that would be
tricky to regulate. Does anybody else have any experience with a similar 2
liter yeast generator and a 10 gallon or other small tank? As yet I have no
problems with algae, but would like to be able to add some Otocinclus.

Thanks for your input,

Ron Barter
Perth, Ontario