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CO2/pH



Chlayne wrote:  "One more question, I am due for a water change and have
my 5 gallon bucket full of tap water.  I added  tsp. baking soda for an
alkalinity of about 100ppm.  When I add the baking soda to the water it
raises the pH to 7.6 (7.2 out of the tap) so how do I get the pH down to
7.0 so I can add the water to the tank?  I am changing 5 gallons in a 29
gallon tank, is this even enough to  worry about?"
Not enough to worry about.  The 18 mg./l CO2 in the tank will bring the
pH of the makeup water down nicely.  You need the extra alkalinity for
your pH to remain around 7.0 with the CO2 level your maintaining.  You
will see that from the chart.  I used to worry about this same point in
my 125 gal. tank.  Because I've made water changes easy, I change out 30
- 40 gallons once every week or 10 days.  I've monitored the pH
continuously (Pinpoint Marine monitor) during water changes and for
overnight after a water change.  With the water level reduced by 1/3 to
 but the CO2 injection rate staying the same (on the sweet spot as
George would say :-)), the pH will drop by as much as 0.2 over an hour
or so (if I'm fooling around cleaning, pruning, rearranging).  Then when
I add the makeup water with extra baking soda, the pH slowly rises from
between 0.2 to 0.4 mg./l as I add the water.  By the next morning I'm
usually back to normal around 7.0.  None of this has ever appeared to
bother my fish.
Sounds like you have everything going well.  Good luck, Steve Dixon