Ammonia is the primary waste product of fish. Ammonia accumulations will perpetuate reddening of the skin and disability of the gills.

Fish suffering with high ammonia accumulations will isolate themselves, stay at the bottom of the pond, clamp their fins, and secrete excess slime. They are also much more susceptible to parasitic and bacterial infection. Ammonia is a common problem in new ponds because the bacteria that would dissolve ammonia are not established. See the Nitrogen Cycle.

Even in established systems, ammonia may still accumulate when the water is cold. Though fishes may be eating and appearing fine, filter bacteria may not have not emerged usefully from hibernation

Ammonia is capable of ionization below pH 7.4 and is less toxic to fishes. Above pH 8.0, ammonia is NOT ionized, and is more toxic. Care should be taken not to increase the pH if ammonia is present. It is then advised to drop the pH.

Water that is warm, high in pH or deprived of oxygen, will have an enhanced toxicity when ammonias are accumulating. pH can change overnight, especially in crowded systems. The pH required for life lies between 5.5 and 8.5. Individual species will have varying pH requirements.

Ignorance of the requirements of each species will result in death.

If the pH is too low, Acidosis results. Symptoms: anorexia, production of excess slime, isolation, and resting on the bottom, streaking of the fins, and even death. If the pH is too high, Alkalosis results. Symptoms: production of excess slime, gasping at the surface and death.

Alkalosis is hard to reverse once it occurs. However, Acidosisis can be corrected once the pH is brought up to a suitable range.

pH contributes to the toxicity of Ammonia. At higher pH values, ammonia is more toxic. Below pH 7.2, most Ammonia is ionized to Ammonium and is far less toxic. This has relevance if you are considering raising the pH in a system with accumulating ammonias.

To correct your pH...

To keep your koi happy, keep your ph above 7.0-7.5

pH can "crash" to 5.5 overnight due to fish, plant and bacterial activity without adequate buffering of water. Caution: fatalities will result.

Baking Soda is a good buffer. Check Total Alkalinity before its use, though. (Use one teaspoon per ten gallons if the TA <100).

Trans Instruments offers two model of pH test instruments. The pocket size ECO pH tester lets you test pH conveniently and easily. The AquaSentry-1 monitor is a 2-in-1 wall mount monitor that allow you to monitor pH and temperature readings24hours non-stop.

Common salt, Sodium Chloride (NaCl) is commonly used in the health care and maintenance of fishes especially Koi. Salt is useful in treating parasites. It will eliminate seven out of nine parasites that are commonly found in Koi pond.

Most fish have an internal salt concentration of 1.0% or 10 parts-per-thousand (ppt) which is higher than their water environment. Osmosis causes water to transfer from the lower salinity of the pond water into the tissues of the fish. Addition of salt will lower the osmosis pressure. This reduces the effort of the fish in eliminating the excess water. The saved energy is then available for use by the fish’s own immune system to fight diseases. On the hand, if the salinity of the water environment is close to the internal tissues of the fish, the osmosis pressure will reverse and cause the fish to die of dehydration.

Salt concentrations between 0.3% and 0.5%(3 to 5ppt) will upset the osmotic balance of some parasites i.e. the parasites’ cells will dehydrate. Salt concentration of 0.3% are effective at detoxifying nitrite and concentration of 0.25% or higher has been used to control string algae. Nevertheless, 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.

Trans Instruments has specially designed the KoiMedic tester to measure the delicate salt concentration in the pond. Two models of your choice measuring in percentage(%) or parts-per-thousand(ppt). The testers are accurate and easy to use. All you need to do is turn it on and dip into the pond water.