Gator :

IMO whoever told you that is wrong assuming your water is as I think you have described ( acid as most in the pine belt). See the info below. In acid water not only does plankton have a tough time but so do the fish. If you are going to run a expir. it is even more important that the water not be the limiting factor. With low alka. you encounter 2 limiting factors at least for your fish . One is high stress related to wide swings in ph (alka. is the shock absorber , buffer to this) and two limited food production(plankton). Plankton is there with or without fertilizer. A limiting factor to its growth is acid water (may also be low fertility). Some ponds like ML's are naturally fertile but need lime to reduce the acid that is limiting its growth. The info below is from the link

http://srac.tamu.edu/tmppdfs/8345539-464fs.pdf

You have seen much on the forum on water quality as to all ponds. Note that it is NOT water quality if you need to fertilize only. Note the info below esp. the first para. and that it does not say only if you need to fertilize.

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.

Phytoplankton are microscopic or
near microscopic, aquatic plants
which are responsible for most of
the oxygen (photosynthesis) and
primary productivity in ponds. By
stabilizing pH at or above 6.5, alkalinity
improves phytoplankton
productivity (pond fertility) by
increasing nutrient availability
(soluble phosphate concentrations).
Alkalinities at or above 20
mg/L trap CO2 and increase the concentrations available for photosynthesis.Calcium and magnesium are essential
in the biological processes
of fish (bone and scale formation,
blood clotting and other metabolic
reactions). Fish can absorb calcium
and magnesium directly
from the water or from food.
However, calcium is the most important
environmental, divalent
salt in fish culture water. The presence
of free (ionic), calcium in culture
water helps reduce the loss of
other salts (e.g., sodium and potassium)
from fish body fluids (i.e.,
blood). Sodium and potassium
are the most important salts in fish
blood and are critical for normal
heart, nerve and muscle function.
Research has shown that environmental calcium is also required to
re-absorb these lost salts. In low
calcium water, fish can lose (leak)
substantial quantities of sodium
and potassium into the water.
Body energy is used to re-absorb
the lost salts. For some species
(e.g., red drum and striped bass),
relatively high concentrations of
calcium hardness are required for
survival.
A recommended range for free calcium
a value of 100
mg/L (250 mg/ L calcium hardness)
matches the calcium concentration
of fish blood. Tests specific
for calcium hardness should be
performed on samples of the
water source being considered for
these animals.
In water with moderate to high alkalinity
(good buffering capacity)
and similar hardness levels, pH is
neutral or slightly basic (7.0 to 8.3)
and does not fluctuate widely.
Higher amounts of CO2 (i.e., carbonic
acid) or other acids are required
to lower pH because there
is more base available to neutralize
or buffer the acid.

ewest