Water And How To Achieve It.
By Jim E. Quarles
For those who keep and spawn discus and other Amazon fishes the need
for soft water, should be second nature to them, but the battle starts
with your efforts of achieve this objective.
How may hard water be softened?
The answer! One may have a better perspective of how to soften hard water
if they understand just what water hardness means.
The term hardness relates to the concentration of ions having a
positive electrical charge of two, called divalent ions. Examples are
calcium ions and magnesium ions. Removing the divalent ions will soften
Hydrated salts such as table salt ( sodium chloride ) is in a solid state
and the ions are tightly bonded to each other. When dissolved in water,
they become electrically charged: they become loosely attracted to each
other. This allows the ions to exchange electrons in random order. When an
element or compound is electrically charged it is said to be ionized.
There are various ways by which water can be softened, namely ( 1.
distillation, 2. reverse osmosis, 3. deionization, and 4. peat
When water is heated to a boil only the water molecule H20 evaporates.
Calcium and magnesium ions are left behind in the heating container. When
steam is directed to a cold area, it condenses and becomes pure water. It
is as soft as water can become at that point. To restore osmotic balance
to the water, some mineral salts need to be added back to the softened
water before it can be life sustaining.
The disadvantage to this method of water purification is the
prohibitive cost of energy to heat the water.
Both saltwater and freshwater fishes cope with the concentration of
salts and dissolved solids in water by a process called osmotic balance.
The cells of the freshwater fish are Salter then their ambient water. By
diffusion, water constantly enters the body of the fish. The membrane of
the fish has the ability to pump the water out in order to maintain its
When the pressure of the water entering the body is greater than can be
pumped out, the fish will die. One the other hand sea water is saltier
then the tissues of the fish. The fish has to constantly drink water, or
die of dehydration. Excess ions taken in along with the water are carried
in the blood and excreted at the gills.
Reverse osmosis involves the application of a semi permeable membrane
where pressure is higher on one side then the other. The pores or openings
of the membrane are so fine that only water molecules, ( H2O ) can pass
through. Calcium and magnesium, being larger than water molecules, are
trapped. The water that has passed through reverse osmosis is almost pure.
The shortcoming of this method of purification is that a very large
volume of water is wasted since it must be discharged from the system.
I might also point out that this method of purification requires that
the source water be under pressure in order to work properly or on a scale
large enough to be of any value.
Deionization is the purification of water by the application of
chemical substances called resins. There are two types of resins: anion
resins which remove negatively charged ions such as chloride, and Cation
resins which remove positively charged ions such as calcium. Synthetic
resins remove electrically charged elements or compounds from water and
exchange it with something else. In this process the ph of the water under
goes a radical change, and close attention is needed. Be prepared to
correct the ph. level before it drops to the danger zone for your
particular fish in the tank.
Dried peat moss acts as natural deionizer. There is an exchange of ions
when water passes through it. It can be used and become cost effective.
However, organic matter such as tannic acid is added to the water causing
discoloration. This may be mitigated by the use of activated carbon. The disadvantage
is that it is messy to work with, and must be replaced after it loses its
ability to acidify / soften the water.
A note to those who keep discus fish. These fish are found only in soft
acidic water in nature. A hobbyist should care enough to provide the same
or should not keep this fish.