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TBAS September 2018 .................... -5-
A good hardness test kit is required for this. The author uses a titrametric
hardness kit manufactured by LaMotte Chemical Co. Continual use of this peat
will result in anaerobic decomposition of it; as the pH rises hydrogen sulfide could
be produced by anaerobic bacterial activity over a period of time. This would be
very toxic to the fish . The author recommends dropping the hardness to 40 ppm;
this may require placing a fresh charge of peat in the canister filter.
About 1 lb. of this peat will soften 55 gallons of Lake Michigan water from
140 ppm down to 40 ppm in a 48-hour period. The pH will drop from 7.4 to
approximately 6.5 during this treatment. The water will turn amber in color. The
amber color can be removed by a flocculating agent such as Filter Aid, manufactured
by Aquarium Products Inc., with no ill effects. It is not advisable to perform
flocculation in water containing live fish if the water is less than 50 ppm total
hardness, as sudden death of the fish from osmoregulatory failure can occur.
Sodium softening is the common household water softening process
which exchanges the sodium ion for whatever other cations may be present in
the tap water. Provided that the feed water is not too high in hardness, it may be
used to soften water for hatching. Such instances would be relatively rare, as I
have tried to soften Lake Michigan water in this way for hatching discus and it did
not work. For this to work, the feed water would have to be quite low in hardness.
The author has observed that keeping discus for a long time in water with a high
sodium concentration causes tiny pin holes in the head area of the fish.
Deionization reduces the ionic strength of the water by removing all the
dissolved salts. A deionizer is commonly composed of two separate cylinders: a
cation cylinder which removes all of the cations; and the following anion cylinder
which removes most of anions if it is the common weak anion resin.
The weak base anion resin will not remove the bicarbonate ion (HCOJ ).
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The acid from the cation resin causes the bicarbonate ion to hydrolyze to free
carbon dioxide (CO ). To remove the CO , the water must be strongly aerated for
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at least six hours before it could be pumped into the fish tanks. Alternatively, a
strong base anion resin cylinder can be used which does remove CO ; however
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it is then necessary to adjust the pH of the water before adding it to the tanks.
There is also the mixed bed deionizer in which both the anion and cation resins
are mixed together. While the mixed bed produces water free of CO , there is no
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way to regenerate the resins when they are mixed together. For this reason it is
too expensive to use the mixed bed process on a large scale.

Reverse Osmosis for Spawning

Killifish: Of the approximately 22 genus of killifish only a few contain species
requiring very low ionic strength water for spawning. This is particularly true of
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