Using herbicides to kill algae and plants
will eliminate high pH problems, but
the benefits are often not worth the
risks and costs. The decomposition
of plants killed by herbicides causes
oxygen depletion and the accumulation
of carbon dioxide and ammonia.
Some herbicides are also relatively toxic
to juvenile aquatic animals. Coppercontaining
products, for example, have a
relatively low margin of safety between
concentrations that kill plants and those
lethal to juvenile fish or prawns. Reducing
plant growth to manage high pH
also conflicts with the goal of fertilization,
which is to increase the production
of natural foods in the pond to support
aquaculture production. Thus, using
herbicides to reduce high pH is usually
a poor substitute for proper pond
management.