Read this link first. Water chemistry involves clarity , turbidity and the effects on the living things in the water.
Many of the principles of chemistry
are abstract (e.g., carbonate-bicarbonate
buffering) and difficult
to grasp. However, a fundamental
understanding of the concepts and
chemistry underlying the interactions
of pH, CO2, alkalinity and
hardness is necessary for effective
and profitable pond management.
There is no way to avoid it; water
quality is water chemistry. https://srac.tamu.edu/index.cfm/event/getFactSheet/whichfactsheet/108/
makes water more acidic. In
ponds with low alkalinity (less
than 20 mg/L as CaCO3) it can
reduce water pH to levels that
may affect fish growth and survival.
In low alkalinity ponds, add
1/2 part hydrated lime for every
part of alum applied in order to
maintain proper pH.
In hard-water ponds (calcium
hardness greater than 50 mg/L),
the water is nearly saturated with
calcium and gypsum may be ineffective.
In that situation, alum will
be the only effective coagulant.
All the coagulants mentioned can
remove phosphorus from water.
As phosphorus is an essential
plant nutrient, it may be necessary
to fertilize the pond after treating
it for turbidity. On occasion, phytoplankton
and clay can mutually
coagulate, so fertilizing to start a
phytoplankton bloom may also
clear water of suspended clay particles.