Online Laboratory

Analysis of the water values in your pond

Welcome to the OASE Online Laboratory. Here you can quickly and easily analyse your water parameters measured with the OASE Professional water analysis set or with the Oase QuickSticks. After entering your data you receive a comprehensive water analysis as to whether your values are in the green range, or whether there is danger for your pond fish. Naturally, with helpful information about how you can quickly restore your pond to balance. You will also receive helpful tips and tricks for typical pond problems such as algae growth or silt.

Parameter selection

pH value pH value

The pH value or "acidity" indicates how acidic or basic (alkaline) there is in water.
It is a dimension for the concentration of acidic or basic components in an aqueous solution.
Pure water reacts neutrally and has a pH value of 7. If acidic components predominate then the pH value drops below 7.
If the basic components predominate then the pH value climbs above 7.

Total hardness Total hardness
°dH

Total hardness is the quantity of magnesium and calcium salts dissolved in the water.
If the quantity of these salts is low the condition is referred to as soft water, if the quantity is high the condition is referred to as hard water.
The specification is made in degrees of German hardness dH; 1° dH equals 10 mg/l dissolved calcium oxide.

Carbonate hardness Carbonate hardness
°dH

Carbonate hardness is the proportion of hydrogen carbonate ions in the pond water and is closely linked with the pH value. The hydrogen carbonates in the pond water take on a buffering function and thus prevent abrupt changes in the pH value. If the proportion of hydrogen carbonate ions is too low, life-threatening reduction (acidity drop) of the pH value can occur for many fish and plants. The hydrogen carbonate ions are in balance with the carbon dioxide dissolved in the pond water. The carbon dioxide is of essential significance as a plant nutrient source for photosynthesis. Consequently the correct carbonate hardness is also extremely important for plant growth.

Ammonium Ammonium
mg/l

The ammonium ion is the result of nitrogen mineralisation. The organically bound nitrogen (e.g. in proteins) in food remnants and excrement is transformed by protein-splitting bacteria and released in the form of ammonium ions. Depending on the pH value, a balance between ammonium ions NH4+ and ammonia NH3 is present in the water. At pH values less than 7, ammonium ions predominate, at pH values greater than 7, ammonia increasingly occurs. Ammonia is extremely dangerous as it impairs the respiration of pond fish and blocks vital functions. Water plants use ammonium as a source of nitrogen. In a healthy and run-in pond filter ammonium is quickly oxidised to nitrate via nitrite by nitrifying bacteria. If this process chain is impaired a sudden increase of ammonia / ammonium can occur.

Ammonia Ammonia
mg/l

The ammonium ion is the result of nitrogen mineralisation. The organically bound nitrogen (e.g. in proteins) in food remnants and excrement is transformed by protein-splitting bacteria and released in the form of ammonium ions. Depending on the pH value, a balance between ammonium ions NH4+ and ammonia NH3 is present in the water. At pH values less than 7, ammonium ions predominate, at pH values greater than 7, ammonia increasingly occurs. Ammonia is extremely dangerous as it impairs the respiration of pond fish and blocks vital functions. Water plants use ammonium as a source of nitrogen. In a healthy and run-in pond filter ammonium is quickly oxidised to nitrate via nitrite by nitrifying bacteria. If this process chain is impaired a sudden increase of ammonia / ammonium can occur.

Nitrite Nitrite
mg/l

In the presence of oxygen, nitrite ions (NO2-) and nitrate ions (N03- occur in a decomposition process from nitrogen compounds, referred to as "nitrification”. In high concentrations nitrite is a toxic intermediate stage for fish and molluscs. Its physiological effect causes an inhibition of oxygen transport in the blood and prevents cellular respiration. As a rule, the nitrite that occurs from ammonium is quickly oxidised to comparatively non-toxic nitrate through nitrifying bacteria. If this bacterial oxidation process is inhibited, e.g. by new filter material, an unfavourable increase in the nitrite concentration can occur.  Nitrite is the end stage of the nitrification process and influences the life and well-being of fish and molluscs to a slight extent. Sources of nitrogen compounds in the garden pond are primarily fish food remnants, excrement and organic decomposition products. Usually nitrate concentrations that occur in the pond are not toxic, however at increased concentrations increased algae growth occurs.

Nitrate Nitrate
mg/l

In the presence of oxygen, nitrite ions (NO2-) and nitrate ions (N03- occur in a decomposition process from nitrogen compounds, referred to as "nitrification”. In high concentrations nitrite is a toxic intermediate stage for fish and molluscs. Its physiological effect causes an inhibition of oxygen transport in the blood and prevents cellular respiration. As a rule, the nitrite that occurs from ammonium is quickly oxidised to comparatively non-toxic nitrate through nitrifying bacteria. If this bacterial oxidation process is inhibited, e.g. by new filter material, an unfavourable increase in the nitrite concentration can occur.  Nitrite is the end stage of the nitrification process and influences the life and well-being of fish and molluscs to a slight extent. Sources of nitrogen compounds in the garden pond are primarily fish food remnants, excrement and organic decomposition products. Usually nitrate concentrations that occur in the pond are not toxic, however at increased concentrations increased algae growth occurs.

Phosphate Phosphate
mg/l

Phosphates are important nutrients for all plants and are indispensable for the metabolism of every living cell. Phosphates get into pond water through fish food, decaying vegetation, and decomposition products of organic matter. But they are also added by water utility companies or they get into the pond from surrounding agricultural areas. A dynamic balance between supply and demand will prevail as long as the phosphate quantity is reduced to a low level by the available plants. It is only the uncontrolled increase in the phosphate content that causes problems, such as strong algae growth. Phosphates are considered a limiting factor for the growth of string algae.

Chlorine Chlorine
mg/l

Some water supply utility companies add chlorine to tap water for disinfection. Even in extremely low quantities chlorine is intolerable for pond fish and other pond inhabitants and must be removed from the water before the water is filled into the pond.


Typical pond problems

Green water
Greyish/brownish, murky water
String algae
Silt deposits
Fish gasping for air

The oxygen content has a crucial influence over the pond biology. Virtually all organisms such as filter bacteria or fish require oxygen dissolved in water. Oxygen deficiency can occur particularly if there is algal bloom, a high proportion of dead biomass, at high water temperatures or if there is insufficient water circulation. Serious water quality issues result in a high number of fish loss.

Algal formation and rumours in fountains
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