Nitrate

The end product of the nitrification process ( nitrification ) is nitrate (NO3-). When ammonia is converted to nitrite by the nitrifying bacteria in the biological filter, nitrate is ultimately formed. Nitrate is a much less dangerous substance than ammonia and nitrite. While ammonia is toxic at levels as low as 0.1 milligrams per liter and nitrite is harmful above 0.2 milligrams per liter, nitrate only becomes a problem for fish health at levels well above 200 milligrams per liter.

What is nitrate?

Nitrate is a nitrogen compound. The standard for Dutch drinking water is a maximum of 50 mg/l. Fortunately, this is never achieved, and values above 10 mg/l are already exceptional. The maximum acceptable daily intake for humans is 3.65 mg per kilogram of body weight per day. So, you can safely drink five liters of tap water a day. As you probably know, nitrates are absorbed by plants as a nutrient. Nitrates are therefore frequently used in the production of fertilizers. Nitrate in the pond can therefore be considered a kind of "Pokon."

Nitrogen cycle incomplete

Since we generally don't have enough plants in our densely populated ponds to absorb nitrate, as is the case in nature ( the nitrogen cycle ), we must take measures to prevent the concentration from rising too high. Although fish can handle fairly high nitrate concentrations, we strive to keep nitrate levels below 50 mg/l. Many koi hobbyists maintain an upper limit of a maximum of 30 mg per liter. Nitrate levels above 50 milligrams per liter create an additional risk of algae explosions, which we want to prevent because they are unsightly. Moreover, these algae can cause slimy plants and fluctuate the pH.

Remove nitrate

To keep nitrate concentrations within limits, the most common way to dilute them is by replacing the pond water with tap water. For a small koi pond, you'll likely need to change 20% of the water per week to achieve the target of a maximum of 30 mg/l nitrate. For a natural pond, this will be considerably less. Measuring is knowing; the nitrate level can be adjusted with a The drop test can be easily determined. Based on the measured values, you can then adjust your water change regimen.

Another method of getting rid of nitrate is to install a Plant filter. Reed species such as yellow iris, in particular, absorb a lot of nitrate. It is important to note that you The plant filter is kept clean, preventing the buildup of debris, which can lead to harmful bacterial growth. Only by harvesting plants (regular pruning) will you actually remove nutrients (nitrates) from your pond.

A third method is to use nitrate resin. This synthetic resin is capable of adsorbing nitrate from the pond. When it is saturated, you can regenerate it with salty and reuse. Place the nitrate resin in a water-permeable bag (for example, a pantyhose, as it contains small granules that you do not want to have loose in your system. Place it in a place where a lot of water flows (for example, in a filter chamber). With 50 grams of salt per liter, you can regenerate the nitrate resin outside the pond by placing it in a bowl with water, salt and a air stone.