Page 26 - Water and the Aquarium

GARGAS: Water and the Aquarium Page 26
GARGAS: Water and the Aquarium Page 26

by Joe Gargas

Just What is Water Hardness???

Water hardness is simply the amount of minerals in the water .
. . specifically the minerals Calcium and Magnesium. Chemically both Calcium
and Magnesium are divalent ions (divalent: salts with two positive charges . . .
there’s your high school chemistry) and generally the hardness of a water sample
is reported in milligrams per liter (same as parts per million, ppm).
Of the two ions measured in hardness: Calcium and Magnesium, Cal-
cium has a more important role in the biological processes of fish. Calcium
is necessary for bone formation, blood clotting and some other metabolic
reactions. Absorption of Calcium can come from two methods: 1) directly from
the water or 2) from the intake of food. In addition to the formation of bones and
other metabolic functions in a fish’s body the presence of free (ionic) calcium at
relatively high concentrations in a culture of water can help reduce the loss of
other salts (e.g. sodium and potassium) from fish body fluids (e.g. blood).
That’s it!!! That’s water hardness, and it is measured quite easily with
test kits that are available at most fish stores. HoweverI don’t think that answers
the question as to why some fish require soft water and some need hard water.
Think about this folks. Let’s go to the depths of the ocean off of Antarctica.
Let's go really deep and find fish that are living in waters that are measured
REALLY cold! You’ve seen them on television . . . they trawl for them and
colorless creatures come up in the nets and in water that is barely a degree or two
above freezing. Ok . . . now, take those fish and put them in the Florida flats in 6
inches of water in the dead of summer where the water temperatures may
approach 90 degrees. Tell it to live and thrive and have babies!!! I know your
intuition tells you it isn’t gonna happen! In fact it will probably be DOA
very quickly. Why . . . because over millions of years these fish have

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