pH
pH expresses the intensity of the
acidic or basic character of the
water. The pH scale is usually represented
as ranging from O to 14.
Conditions become more acidic as
pH values decrease and more
basic as they increase. At 77°F, pH
7.0 is the neutral point. The pH of
most fresh waters is a function of
total alkalinity and dissolved carbon
dioxide concentration. Generally,
if levels of those two variables
are within the desired range, pH
will be between 7.0 and 8.5, which
is the desired pH range for incubating
eggs and rearing fry.
An important exception to this
general rule exists when surface
waters containing dense submersed plant communities are
used as a water supply. During
sunny afternoons, rapid carbon dioxide
removal by photosynthesizing
plants may cause pH values to
temporarily rise above pH 9. In extreme
instances, values well above
pH 10 have been recorded. Exposure
to pH-values above 9 are undesirable
and even short-term
exposure to waters of pH 10 or
above may kill fry and reduce egg
matchability. Vigorous aeration of
such waters will add some carbon
dioxide to the water and somewhat
reduce the pH, but this reaction
is not rapid enough to be
effective in extreme circumstances.
The best solution is to avoid the
use of surface waters that contain
dense stands of submersed plants.
pHpH expresses the intensity of theacidic or basic character of thewater. The pH scale is usually representedas ranging from O to 14.Conditions become more acidic aspH values decrease and morebasic as they increase. At 77°F, pH7.0 is the neutral point. The pH ofmost fresh waters is a function oftotal alkalinity and dissolved carbondioxide concentration. Generally,if levels of those two variablesare within the desired range, pHwill be between 7.0 and 8.5, whichis the desired pH range for incubatingeggs and rearing fry.An important exception to thisgeneral rule exists when surfacewaters containing dense submersed plant communities areused as a water supply. Duringsunny afternoons, rapid carbon dioxideremoval by photosynthesizingplants may cause pH values totemporarily rise above pH 9. In extremeinstances, values well abovepH 10 have been recorded. Exposureto pH-values above 9 are undesirableand even short-termexposure to waters of pH 10 orabove may kill fry and reduce eggmatchability. Vigorous aeration ofsuch waters will add some carbondioxide to the water and somewhatreduce the pH, but this reactionis not rapid enough to beeffective in extreme circumstances.The best solution is to avoid theuse of surface waters that containdense stands of submersed plants.
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