Alkalinity (Carbonate hardness) in Ponds
Alkalinity, often referred to as "carbonate hardness," or German carbonate hardness, is the measure of carbonate and bicarbonate concentrations in your aquarium water. Alkalinity is a measure of the ability of a solution to neutralize acid without changing the pH. It both controls and maintains water pH. Carbonate hardness is measured in degrees (dKH), parts per million of calcium carbonate (ppm CaCo3), or milligrams per liter (mg/L).
Alkalinity is not the same as pH because water does not have to be strongly basic (high pH) to have high alkalinity. Alkalinity is related to the amount of dissolved calcium, magnesium, and other compounds in the water and as such, alkalinity tends to be higher in "harder" water. Alkalinity is naturally decreased over time through bacterial action which produces acidic compounds that combine with and reduce the alkalinity components.
In an established pond, the ideal Alkalinity measurement should be around 100 ppm. Readings from 50 to 200 are acceptable.
High alkalinity is normally prevented by routine water change outs assuming the water being replenished has a lower alkalinity than the pond water.
Ponds with vinyl liners or of fiber glass construction tend to show a decrease in alkalinity over time and may need supplements to maintain an acceptable level. Raise alkalinity by adding Calcium Carbonate, concrete blocks, oyster shells, limestone, or even egg shells.
Established ponds will normally maintain their equilibrium pH value if sludge and decaying organic material is routinely removed from the pond, mechanical filter, and biological converter. Scheduled water change outs (10% per week for a small pond, less for larger ponds) are also helpful.
More Pond Water Chemistry ↓
Where does the ammonia originate from?
Pond fish produce waste in the form of ammonia, which is released into the water through the gills. Ammonia can also originate from the dead and decaying plant material in the pond or from uneaten food, which is left in the water.
In an established pond...
Acceptable concentration 0
A gas widely used in the disinfection of water and as an oxidizing agent for organic matter, manganese, iron, and hydrogen sulfide.
Chlorine is known to react with organic matter in the water to form trihalomethanes (THMs), a suspected carcinogen.
Sometimes referred to as an algae bloom, Another factor which can influence the pH of the water is the presence of plants, most notably if there is an algae bloom in the pond. During the hours of daylight, plants produce nutrients directly from carbon dioxide dissolved in the water and the...
Nitrate is the final product from the breakdown of ammonia released by the fish.
Nitrate is not especially harmful to freshwater fish but is a potent plant fertilizer and can contribute to the growth of unsightly and unwelcome algae, such as green water or blanketweed. Ideally,...
As the ammonia in the water begins to reduce, the secondary break down product, nitrite will begin to increase and this is also very poisonous to fish.
Nitrite is a skin irritant and will cause the fish to display symptoms of irritability such as rubbing themselves, jumping, or even skimming...
The pH is in all respects a measure of acidity and alkalinity, pH 0 - 6.99 is acid; pH 7.0 is regarded as neutral and pH 7.01 - 14.0 is alkaline. On the whole the pH is not generally a problem but it can have a profound effect on the toxicity of ammonia. Alkaline water, that is with a pH of over...
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...
Partial water change outs can reduce the amount of anything dissolved in the water but not totally remove it. Although it is sometimes necessary, draining and refilling a pond should only be used as a last resort!
Drain some water from the pond before refilling; ideally pumped or siphoned from...