Why pay $10 - $20 on "pond salt" that is available at local water
gardening stores when you can buy a 40lb bag of "solar salt" crystals at
Home Depot for $5.00 !!! I've been using solar salt in my pond this year
and have achieved the same results that I had when I used the more expensive
"pond salt". Inexpensive and quite pure solar-dried or kiln-dried salt used
in home water softeners is available at most supermarkets and home
improvement centers. Do not use pelletized water softener salt that has
binding agents or any type of iodized salt. For those of you asking, "Why do
I need salt in my pond?" - Common salt, sodium chloride, NaCl, has been
termed "The KOI Wonder Drug". A misnomer perhaps, but salt is a proven
staple in the health care and maintenance of Koi worldwide. Koi maintain an
internal concentration of salt in their body fluids higher than that of
their liquid environment. Osmosis causes water to transfer from the lower
salinity of the pond water into the tissues of the fish. This additional
water build up must be eliminated by the kidneys. Although salt in higher
concentrations may slow some disease causing bacterial growth in the pond,
the predominantly accepted theories ascribe the primary benefits of salt to
lowering the osmotic pressure. This reduces the effort the fish must expend
in eliminating the excess water. The saved energy is then available for use
by the fish's own immune system to take care of other potential problems.
The presence of salt also helps counteract any nitrite toxicity. In some
cold climate areas, it is added in the Winter to lower the freezing point of
the water.

A salinity test kit is available at most water gardening stores. The
procedure in the kit can be used in adding the solar salt instead of pond
salt. I've seen too many people with fish problems not even consider the
lack of salt as a possible problem. Soooo, for you pond lovers, check your
pond's ph and salinity and have healthy fish all year!

PondMan
MD