Re: NANFA-L-- hardness and pH

Laura Burbage (
Wed, 31 Aug 2005 06:47:48 -0700 (PDT)

Thanks Bruce. I always struggle with the
pH/hardness/carbonate/bicarbonate concept.

Since pH isn't a good measure of what is going on,
should I ignore it in this case? Somehow that
feels... unwise. If I want to raise my hardness to
around 6 or 8, and ensure that my fish are OK, how
should I proceed (inexpensively)?


Date: Mon, 29 Aug 2005 10:11:29 -0400
From: "Bruce Stallsmith" <>
Subject: Re: NANFA-L-- hardness and pH

Strong photosynthesis will raise the pH of water by
removing dissolved
gas (not common anyway) and bicarbonate ions, the most
common form of
CO2-derived compounds around neutral pH. Plant systems
aren't as able
to use
carbonate ions, CO3--, for photosynthesis so carbonate
dominates the
buffer system and raises pH. When I used to monitor a
pond's pH with a
computerized system in the summer we found that pH
could hit 10 on a
bright summer day, before returning to around 6.1 at
night as CO2 was
to accumulate in the water again as photosynthetic
demand decreased.
this was in a pond considered to be sensitive to

pH is a secondary indicator of water quality processes
rather than a
parameter. Total Dissolved Solids (TDS) and the
various hardness
tell you much more about buffers and balances in a
body of water.

- --Bruce Stallsmith
along the Tennessee, waiting for Katrina
Huntsville, AL, US of A

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