Acidity (pH): 6,5 – 8,5
This value affects the wellbeing of your plants and fish. The value must be between 6,5 and 8,5.
Carbonate hardness (KH): 6 -10° dH
Carbonate hardness (KH) is also called temporary hardness. KH buffers the pH, it stabilizes pH. Nitrifying bacteria use up the KH in converting ammonium into nitrite and nitrate (1 part ammonia costs 7 parts KH). When the KH reaches 3° dH the whole nitrification process stops.
General hardness (GH): 8-12° dH
The general hardness of water is the total calcium and magnesium content. For water plants to grow well it is important that this value is not lower than 8° dH (140 ppm).
Ammonia/Ammonium: 0 mg/l
Fish secretions and the breakdown of organic materials cause ammonium to be present in the pond water. If the pH value is too high, ammonium is converted into ammonia, which is toxic and causes health problems for the pond life. This value must therefore be 0. Ammonium is already dangerous for fish at 0,1 mg/l. Bacteria convert ammonium into nitrite.
Nitrite: 0 mg/l
Nitrite is produced when ammonium is broken down. Nitrite is less toxic than ammonium, but can also cause health problems in the pond. The nitrite value in the pond should therefore also be 0. Bacteria convert nitrite into nitrate.
Nitrate: < 30 mg/l
While nitrate is not toxic, it is regarded as an undesirable substance in the pond. It is a source of food for algae and inhibits the growth of small fish. It also increases stress levels in fish. Bacteria convert nitrate into nitrogen gas (N2).
Phosphate: < 0,03 mg/l
For fish ponds it is less important as we can treat (floating green)algae with UV-C units and blanket weed (string algae) with water treatment products. For ornamental ponds / swimming ponds the phosphate level should be lower than 0,03 mg/l to keep the algae under control.