The important question of whether or not to add salt to your pond is often confusing for beginners and forgotten by experienced pond-keepers. To newbies and pro's alike we have this to say:

"Add Salt Today to Keep the Fish Doctor Away"
True, there are some negative effects of higher salt levels on plants in the pond, but overall we think it is absolutely the very best thing you can add to your pond in terms of keeping your fish happy and healthy. Salt acts as a natural 'stress coat' and essentially thickens the slime coat on the fish's body - which is it's own natural defense system against bacteria and parasites.

Salt is also very effective in killing bacteria and parasites in the pond. When added in proper doses, salting your pond can dramatically reduce the threat of disease affecting your fish.

It's just like with humans - we are always exposed to the common cold cells in their body, but can usually resist if their immune system is strong. Similarly, pond fish and KOI are always exposed to some degree of parasite and bacteria presence in the pond, but by keeping their immune system strong and their slime coat thick, you shouldn't have any problems.

Pond fish actively maintain a natural balance of electrolytes in their body fluids. Electrolytes such as potassium, sodium, chloride, calcium and magnesium are removed from the water by chloride cells located in the gills. These electrolytes are essential for the uptake of oxygen and release of carbon dioxide and ammonium across gill membranes.

The lack of electrolytes can cause serious health problems to the fish. Pond Salt is an all natural salt, providing the essential electrolytes fish need to survive. Pond Salt is not just a table salt ( sodium chloride ). It is made from evaporated sea water. Evaporated sea water contains the necessary electrolytes pond fish need. 
How Pond Salt helps Improve Gill Function to Reduce Stress....

During periods of disease and stress, healthy gill function is disturbed. This can lead to the loss of electrolytes through the gills, sometimes called osmotic shock. Osmotic shock interrupts healthy gill function by reducing the intake of oxygen and the release of carbon dioxide and ammonium from the fish. Pond Salt reduces the risk of osmotic shock by supplying natural electrolytes through the chloride cells in the gills.

Nitrite Toxicity

Overcrowding and overfeeding can lead to elevated nitrite levels especially in newly set-up ponds. The nitrite ion NO 2 enters the gills and prevents the blood from carrying oxygen resulting in nitrite toxicity or "methemoglobinemia". Pond Salt will temporarily block the toxic effect of nitrite.

All natural Pond Salt is safe and non-toxic to all pond fish when used as directed. Pond Salt can be used safely with Pond Care water conditioners, filtration materials and fish foods.

Directions for Use:

1. When used as a general tonic for fish, and as a stress reducer, add 2 -1/2 cups full (728g) of Pond Salt for each 100 gallons (378 L) of pond water. Sprinkle salt evenly around the perimeter of the pond. Avoid any contact between salt crystals and pond plants. If this is not feasible, pre-dissolve salt first.

IMPORTANT NOTE:Once added to a pond, salt does not evaporate and is not filtered out. Pond Salt should only be added as directed; with each water change, or when fish have been treated with medications.

2. When used to reduce stress in separate treatment tanks or during fish transportation, use 4 tablespoons full (95.2g) of Pond Salt for each 10 gallons (37.8L) of water.