Koi Medic Salinity Meter Pen

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.

Salt can cause pond plant damage as the
concentration increases. Floating plants, (water hyacinth,
water lettuce, etc.) are affected at lower concentrations than
most bog plants. Related, salt may provide some minor control
of algae in the higher concentrations.

Salt has been used on such a large scale and usually for no reason that
most parasites are resistant to it. However it still has it's place.
Using it at a .6% - .7% level is excellent when bringing in new fish to a
quarantine tank.  Salt is effective on all microscopic parasites at this
level. At least it knocks them back a bit giving you some time to
determine what further treatments, if any, which you might use. See
statements below for an overview on salt:

Salt is known to protect fish from nitrites. The percentage of salt in
this case is .15%. When adding fish to a pond or q-tank pay attention to
ammonia and nitrites!

Salt is required, at least so the story goes, when using Elbagin(a
Japanese water column antibacterial agent very similar to Nitrofurazone).
The percentage of salt in this case is .6%.

Salt will aid in osmotic regulation of an immuno-depressed fish as well
as koi with damaged gill tissue. It is used at a rate of .15% to .3%.
New imports, as well as fish with bacterial infections are sometimes
treated to aid their recovery. The percentage of salt used this way
varies.  Be aware that salt may adversely affect some medications. 

Several parasites can still be controlled successfully with salt. The
percentage of salt in this case is .6%. The treatment is not too
temperature dependent and the duration of the treatment should be 14
days. Some strains of microscopic parasites are no longer deterred by
salt.

For informational purposes here is how to calculate salt:

.1% salt in 100 US gallons is .8333 pounds.

.1% salt in 1000 US gallons is 8.333 pounds.

.3% salt in 100 US gallons is 2.5 pounds.

.3% salt in 1000 US gallons is 25 pounds.

.6% salt in 100 US gallons is 5.0 pounds.

.6% salt in 1000 US gallons is 50 pounds.

.15% salt in one US ton(264 gallons) is 3.313 pounds.(preferred for reduced nitrite uptake)

Aquariums or qt - Apply one teaspoon of non iodized table salt per gallon of water every 12 hours for three treatments:

3 tsp per gallon for .3%.

6 tsp per gallon for .6%

Salt and Nitrites:

Dosage is .15%. Salt will slow if not stop the uptake of nitrites.