Summary
Different management practices can be
used to reduce high pH and minimize
the risk of pH toxicity to freshwater fish
and crustaceans. The choice of method
should be based upon the specific need,
and a combination of approaches might
be most effective. Planning ahead can
help avoid many problems. Pond water
should have adequate levels of alkalinity
and hardness for the species under
culture, and those levels should not
be widely disproportionate. Stocking
should be done at the right time of
year and right time of day to reduce
risks. Adding small amounts of easily
decomposable organic matter can be an
effective preventive measure because its
decomposition produces carbon dioxide
and reduces pH for a longer period.
Emergency treatments to rapidly reduce
high pH are fraught with problems and
most have only temporary benefits because
the underlying cause of the problem
is not being properly addressed.
The careful use of alum is probably the
safest and most dependable emergency
treatment.